JP4174466B2 - Color camera color adjustment system and method, and character / graphic recognition method using this system - Google Patents

Description

  The present invention relates to a color adjustment system for a color camera that performs color adjustment of a red component, a blue component, and a green component. In particular, the present invention relates to, for example, a color camera color adjustment system that performs color adjustment to enable recognition of characters and figures written in blue on a red background, and a character / graphic recognition method using this system. .

  Conventionally, a white balance adjustment operation is performed as a color adjustment operation of a color camera. This white balance adjustment operation integrates the red, blue, and green components of the shot image so that white objects can be shot white without being affected by the color temperature of the light in the shooting environment. The white balance is adjusted by adjusting the red component amplification factor, the blue component amplification factor, and the green component amplification factor so that the green component becomes the same.

On the other hand, when characters, one-dimensional and two-dimensional barcodes are printed, they are usually written in black on a white background.
When the white part and black part are written, the white balance color adjustment generally performed in color cameras maximizes the brightness difference between the white part and the black part. When recognizing, the conventional recognition rate is not affected.

  However, in the case of characters / graphics written in black on a white background, for example, in the case of characters / graphics written in blue on a red ground, the characters / graphics written in red on the background and blue There is a problem that the same luminance difference as that of characters / graphics written in white and black background cannot be obtained. That is, there is a problem that the recognition rate of characters / graphics written in blue on a red background is significantly reduced.

  In the conventional image display device, in order to prevent color separation from being detected as a color component by a visual integration effect, color signals are output in a different color order for each field. Color extraction means for extracting light of three primary colors of R, G, and B and supplying it to the DMD, time division multiplexing circuit for supplying the DMD after time division multiplexing of the input G, R, and B signals, and time division multiplexing circuit The color sequence control circuit controls the operation of the light source, and the light from the light source is reflected by the DMD through the color extracting means and projected onto the screen so that an image is displayed (for example, Patent Documents). 1).

However, in Patent Document 1, color signals are output in a different color order for each field so that color separation is not perceived as a color component due to a visual integration effect. Color adjustment that improves the recognition rate of characters and figures written in blue on a red background cannot be performed.
Further, in the conventional image processing apparatus, by utilizing the characteristics of the color document image, the color document image is input in order to recognize the characters of the color document image with a simpler configuration, and the character recognition of the color document image is performed. In a character recognition device to perform, a gray conversion circuit that converts a maximum value or a minimum value of a plurality of color component signals in a color signal of each pixel constituting a color document image into a gray image as a representative value of the pixel, and a gray conversion circuit Some include a binarization circuit that binarizes the converted gray image and a character recognition circuit that performs character recognition from the binary data of the binarization circuit (see, for example, Patent Document 2).

However, in the above-mentioned Patent Document 2, a character is recognized by using the feature of a color document image having a color character on a white background. As described above, for example, the character is described in blue on a red background. Color adjustment that improves the recognition rate of characters and graphics cannot be performed.
Further, in the conventional image correction apparatus, an image correction apparatus and an image correction program capable of improving the recognition rate based on the distribution status of the RGB data of the digital image are provided. When the image data is input, the input image data is transferred to the RAM and expanded as a bitmap image. When the expansion to the RAM is completed, the values of R, G, and B to be processed are determined according to the image correction processing program. And R, G, and B values of the surrounding data are compared to determine whether the processing target is a dimming process target (background) or a character (foreground), and the dimming process target is corrected by making the amount of light uniform (For example, refer to Patent Document 3).

However, in the above-mentioned Patent Document 3, the recognition rate is improved based on the distribution status of the RGB data of the digital image. As described above, for example, recognition of characters / graphics written in blue on a red background is performed. Color adjustment that improves the rate cannot be performed.
Also, conventional devices provide a method and various processes for removing color from a multi-color image document, so that all color information for all pixels of the document image is provided simultaneously, with respect to all pixels PEL. The image signal of all given colors is analyzed so that for all pixels, this image signal for this color with the lowest contrast for the background of the image document is selected. (For example, refer to Patent Document 4).

However, in Patent Document 4, the color is removed from the multicolor image document. However, as described above, for example, color adjustment is performed to improve the recognition rate of characters and figures written in blue on a red background. I can't.
Further, in the conventional image processing apparatus, in order to easily set each amplification factor when amplifying the R, G, and B signals from the image reading sensor, the image reading unit 201-3 reads the standard white plate. The obtained RGB signals are amplified by amplifiers in the analog processing circuits 118 to 120, respectively. The amplification factor of each amplifier can be set in three stages of standard and its ± α. First, it is set to standard, and the output of the amplifier that has obtained an intermediate level among the RGB signals at that time becomes a predetermined value. In this way, the amount of light irradiating the white plate is adjusted. After that, by setting the amplification factor of each amplifier of the remaining two signals so as to maximize each amplification output without being saturated, the levels of the RGB signals are adjusted uniformly. (For example, refer to Patent Document 5).

However, in the above-mentioned patent document 5, each amplification factor is set when each of the R, G, and B signals from the image reading sensor is amplified. As described above, for example, blue is described on the red background. Color adjustment that improves the recognition rate of the printed characters / graphics cannot be performed.
In addition, in the conventional optical character reader, in order to provide an OCR that performs accurate color determination and reliably removes the dropout color without being affected by the relative output level difference of the color image sensor, red, The green and blue color signals rd, gr, and bl are given to the color determination units 31 to 34 and the maximum value detection unit. The color determination unit performs color determination based on reference values of different classes, and detects the maximum value. The unit detects the maximum value max of the color signal, the peak detection unit detects the peak value peak from the maximum value max, the level determination unit determines the class of the color signal level from the peak value peak, and the determination result csel is color-coded. Based on the determination result csel, the color information selection unit selects the color determination result bsel corresponding to the color signal level from the color determination result output from the color determination unit, and the luminance signal selection unit So that selectively outputs the luminance signal bw based on the selected color determination result bsel. (For example, refer to Patent Document 6).

However, in the above-mentioned Patent Document 6, an OCR that performs accurate color determination and reliably removes the dropout color without being affected by the relative output level difference of the color image sensor is provided. For example, it is not possible to perform color adjustment that improves the recognition rate of characters / graphics written in blue on a red background.
Further, the conventional image processing apparatus relates to an image processing apparatus and an optical character reading apparatus that extract only a necessary image from a color image, and relates to an image processing apparatus and an optical character reading apparatus that can reliably extract a required image. For the purpose of providing, the color image input unit reads the color image of the form with the three primary colors of RGB, the maximum value and the minimum value are extracted from the components of the three primary colors read by the extraction circuit, and the extracted maximum value and A value obtained by dividing the minimum value by the maximum value as the brightness V value and the minimum value divided by the maximum value is extracted as the saturation S value, the saturation is compared with the S threshold by the S value comparison circuit, and the S threshold is selected by the V threshold selection circuit. One V threshold is selected from the two large and small V thresholds according to the comparison result of the value comparison circuit, and the V threshold selected by the V threshold selection circuit is compared with the brightness extracted by the extraction circuit to determine white or black Shi And so as to extract a character image from a color image. (For example, refer to Patent Document 7).

However, in Patent Document 7, a character image is extracted from a color image. As described above, for example, a color that improves the recognition rate of characters / graphics written in blue on a red background. Adjustment cannot be made.
Further, in the conventional image reading apparatus, a color image signal output from a CCD linear image sensor is provided in order to provide an image reading apparatus that adjusts the illumination light amount of a lamp and the gain of an amplifier in accordance with the type of transparent original. An amplifier that converts the output signal of these amplifiers into a digital signal, a light source that illuminates the transmissive original, a detachable optical filter that changes the amount of illumination of the light source, and a transmissive original There is a configuration provided with control means for calculating the control value of the illumination light quantity of the light source and the amplification gain control value of the amplifier, which are required from the characteristics of the filter according to the type of filter. (For example, refer to Patent Document 8).

However, Patent Document 8 provides an image reading apparatus that adjusts the illumination light amount of the lamp and the gain of the amplifier in accordance with the type of the transparent document. Color adjustment that improves the recognition rate of characters / graphics written in blue cannot be performed.
In addition, with conventional document photographing devices, both characters are clear when photographing a document in which copied handwritten characters and preprinted characters are mixed, such as a standard-type copy-type handwritten document. In order to provide a document photographing apparatus that can generate an image that appears in the image processing unit, the image processing unit is a component range selection amplification unit, the R component range selection amplification unit receives R component data and R component amplification parameters, The R component data related to the range of the predetermined area frame selected by the parameter coordinate data is amplified according to the parameter amplification degree data and output as R component image correction data, and the image processing unit emphasizes the blue line Is added to the input data, the R and G components that are darker than the ground color level are amplified and lowered in the darker direction (in the direction of lower brightness). (For example, refer to Patent Document 9).

  However, in Patent Document 9 described above, even when a document in which copied handwritten characters and preprinted characters are mixed is photographed, such as a standard-type copy-type handwritten document, both characters are clearly displayed. Although a document photographing apparatus capable of generating an image that appears is provided, as described above, for example, color adjustment that improves the recognition rate of characters and figures written in blue on a red background can not be performed.

Japanese Patent Laid-Open No. 2000-077862 JP 2001-351068 A JP 2004-185183 A Japanese Patent Laid-Open No. 06-195509 JP 09-261494 A JP 09-265510 A Japanese Patent Laid-Open No. 10-051655 JP-A-11-168601 JP-A-11-345318

Therefore, in view of the above problems, the present invention provides a color camera color adjustment system and method for performing color adjustment that enables recognition of characters and figures written in blue on a red background, for example, and this system. An object is to provide a method for recognizing characters and figures used.
Another object of the present invention is to add a new function of the present invention to the white balance function, so that the configuration is not complicated.

In order to solve the above problems, the present invention provides a color adjustment system for a color camera that performs color adjustment of a red component, a blue component, and a green component. An image sensor that converts a red component, a green component, and a blue component of a photographed image obtained by focusing and forming an image on which characters and figures are collected by a lens, and a red component and a green converted by the image sensor. An amplifying unit for amplifying the component and blue component electrical signals, a luminance calculating unit for obtaining luminance from the red, green and blue component electrical signals amplified by the amplifying unit, and the red amplified by the amplifying unit A maximum luminance storage unit for storing the maximum luminance of the electrical signal of the component, the green component, and the blue component as the luminance of one of the ground, the character, and the figure; and the red component, the green component, and the blue amplified by the amplification unit The minimum luminance of the electrical signal of the component, And the minimum luminance storage unit to be stored as the other luminance of the characters and figures, and the luminance difference between the maximum luminance stored in the maximum luminance storage unit and the minimum luminance stored in the minimum luminance storage unit. The luminance difference storage unit for storing the difference and the amplification factor for amplifying the red component, green component, and blue component electrical signals of the amplification unit are set as initial values to a minimum value, and one of the amplification factors is sequentially maximized. e Bei wherein the set value the ground through the luminance difference storage unit characters, and a maximum luminance difference acquired color adjustment unit for performing color adjustment so as to obtain the maximum luminance difference between figure, the maximum luminance difference The acquired color adjustment unit sets one of the amplification factors to the maximum value, and determines that the image is only the ground when the luminance difference stored in the luminance difference storage unit is only the maximum luminance difference. The acquisition operation is stopped and recorded in the brightness difference storage unit. When the difference in luminance is only the minimum luminance difference, one amplification factor is returned to the initial minimum value, and the other maximum amplification factor is set to the maximum value to obtain the next maximum luminance difference. A color camera color adjustment system is provided.

In addition, the pre-Symbol maximum luminance difference acquired color adjustment unit, the luminance difference stored in the brightness difference storage unit the number of pixels is the maximum luminance difference in the case of more than half of the number of pixels of pickup image, It is determined that the pixel having the maximum luminance difference forms one of the ground, the character, and the graphic, and the pixel having the minimum luminance difference forms the other of the ground, the character, and the graphic.

  Further, the maximum luminance difference acquisition color adjustment unit fixes an amplification factor for amplifying any one of the electrical signals of the red component, the green component, and the blue component of the amplification unit to a minimum value that is an initial value, The amplification factor of two electrical signals is sequentially set to the maximum value, and the number of pixels when the luminance difference stored in the luminance difference storage unit is the maximum luminance difference is compared with the number of pixels when the luminance difference is not the maximum luminance difference, Judging the number of pixels of the ground and the number of pixels of the character and the figure, if the number of pixels of the character and the figure is larger than the number of pixels of the ground, the luminance difference stored in the luminance difference storage unit is inverted, The brightness of characters and figures is the brightness of the ground, and the brightness of the ground is the brightness of the characters and figures.

  Furthermore, the present invention provides a color camera color adjustment system that performs color adjustment of a red component, a blue component, and a green component, and a character of the other color on the background of one color of red, green, blue, yellow, cyan, and magenta. An image sensor for converting a red component, a green component, and a blue component of a photographed image formed by focusing an image on which a graphic is described by a lens into an electric signal, and a red component and a green component converted by the image sensor An amplifying unit for amplifying the blue component electric signal, a luminance calculating unit for obtaining luminance from the red component, green component, and blue component electric signals amplified by the amplifying unit, and a red component amplified by the amplifying unit A maximum luminance storage unit for storing the maximum luminance of the electrical signal of the green component and the blue component as one luminance of the ground, the character, and the figure, and the red component, the green component, and the blue component amplified by the amplification unit Before the minimum brightness of the electrical signal As the other brightness of the ground, the character, and the figure, the minimum brightness storage unit that stores the maximum brightness difference between the maximum brightness stored in the maximum brightness storage unit and the minimum brightness stored in the minimum brightness storage unit A luminance difference storage unit for storing the luminance difference and an amplification factor for amplifying the red component, green component, and blue component electrical signals of the amplification unit are set as initial values to a minimum value, and one of the amplification factors is sequentially set. Color adjustment is performed so that the maximum brightness difference between the ground, the character, and the figure is set via the brightness difference storage unit and the brightness difference stored in the brightness difference storage unit is the maximum brightness. Compare the number of pixels in the case of difference with the number of pixels in the case of not being the maximum luminance difference, determine the size of the number of ground pixels and the number of pixels of characters and figures, and the number of pixels of characters and figures is the number of pixels of ground Stored in the brightness difference storage unit. Color camera color adjustment characterized by comprising a maximum brightness difference acquisition color adjustment unit that inverts the luminance difference and uses the luminance of characters and figures as the luminance of the ground and the luminance of the ground as the luminance of the characters and graphics Provide a system.

Further, the maximum luminance difference acquisition color adjustment unit sets one of the amplification factors to a maximum value and the luminance difference stored in the luminance difference storage unit is only the maximum luminance difference, or the minimum luminance difference In the case where only one amplification factor is obtained, one amplification factor is returned to the initial minimum value, the other amplification factor is set to the maximum value, and the next maximum luminance difference is obtained.
Further, the maximum luminance difference acquisition color adjusting unit provides information requesting the image sensor to perform time division multiplexing, and the image sensor converts red, green, and blue component electrical information converted based on the provided information. The signal is time-division multiplexed, and the maximum luminance difference acquisition color adjustment unit sets the amplification factor for amplifying the time-division multiplexed red component, green component, and blue component electrical signals to the amplifier, and the amplification unit The red component, green component, and blue component electrical signals time-division multiplexed by the image sensor are amplified at the amplification factor set by the maximum luminance difference acquisition color adjustment unit.

Further, in the color adjustment method of a color camera that performs color adjustment of red, blue, and green components, an image in which characters and figures of the other color are described on the ground of one color of red, green, and blue is a lens. Converting the red, green, and blue components of the captured image focused and formed into an electrical signal, amplifying the converted electrical signals of the red, green, and blue components, respectively, and amplifying Determining the luminance from the electrical signals of the red, green, and blue components, and the maximum luminance of the amplified electrical signals of the red, green, and blue components to determine the luminance of one of the ground, the character, and the figure. And storing the minimum luminance of the amplified red, green, and blue electrical signals as the other luminance of the ground, the character, and the figure, and the stored maximum luminance. And the maximum brightness difference stored in the minimum brightness A step of storing the difference as a degree of difference and an amplification factor for amplifying the electrical signals of the red component, green component and blue component, respectively, as an initial value, and setting one of the amplification factors as a maximum value in sequence. Adjusting the color so as to obtain the maximum luminance difference between the character and the figure, and setting the one amplification factor to the maximum value, and the stored luminance difference is only the maximum luminance difference When it is determined that the image is only the ground and the operation of obtaining the maximum luminance difference is stopped, when the stored luminance difference is only the minimum luminance difference, one amplification factor is returned to the initial minimum value, and the other amplification is performed. And a step of acquiring the next maximum luminance difference by setting the rate to the maximum, and providing a color adjustment method for a color camera.
Furthermore, the present invention provides a character / graphic recognition method using a color adjustment system of a color camera, wherein the luminance difference stored in the luminance difference storage unit is input and characters and figures are recognized.

As described above, according to the present invention, the white balance operation is used for the normal photographing operation, and the character / graphic recognition color tone operation of the present invention is used for the character / graphic recognition operation. It is possible to avoid a reduction in the recognition rate of characters / graphics due to the color and the background color.
For example, in the case of characters and figures written in blue on a red background, when shooting with a color camera and extracting the luminance signal, there is almost no difference in luminance between the background portion and the characters / graphics portion, using the luminance signal, Although the figure cannot be recognized, the amplification factor of the red component, green component, and blue component is adjusted, the brightness difference between the background part and the text / graphic part is increased, and the characters and figures written in black on the white background are recognized. It has become possible to extract the same luminance signal.

In addition, any one of the amplification factors of the red component, the green component, and the blue component may be fixed, and the other two amplification factors may be adjusted to increase the luminance difference between the background portion and the character / graphic portion. Is possible.
Furthermore, not only red, green, and blue components, but also characters and figures can be recognized by shooting images that include intermediate colors of yellow, cyan, and magenta.
Furthermore, it is possible to time-division-multiplex the electrical signals of the red component, the green component, and the blue component, and to avoid complication of the circuit configuration for adding a new function according to the present invention to the color camera.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration of a color adjustment system for a color camera according to the present invention. Throughout the drawings, the same components are denoted by the same reference numerals and symbols.
As shown in the figure, the color adjustment system of the color camera is provided with a lens 101, and the lens 101 has a function of condensing a captured image.

An image sensor 102 is provided at the rear of the lens 101. The image sensor 102 forms a photographed image collected by the lens 101, and converts the red, blue, and green components of the formed image into electrical signals. It has the function to do.
A red component amplifier 103, a green component amplifier 104, and a blue component amplifier 105 are connected to the image sensor 102.

The red component amplifier 103 has a function of amplifying the red component electrical signal converted by the image sensor 102.
The green component amplifier 104 has a function of amplifying the green component electrical signal converted by the image sensor 102.
The blue component amplifier 105 has a function of amplifying the blue component electrical signal converted by the image sensor 102.

A red component A / D (Analog to Digital) converter 106, a green component A / D converter 107, and a blue component A / D converter 108 are connected to the red component amplifier 103, the green component amplifier 104, and the blue component amplifier 105, respectively. Is done.
The red component A / D converter 106 has a function of converting the electrical signal of the red component amplified by the red component amplifier 103 into a digital signal.

The green component A / D converter 107 has a function of converting the electrical signal of the green component amplified by the green component amplifier 104 into a digital signal.
The blue component A / D converter 108 has a function of converting the electrical signal of the blue component amplified by the blue component amplifier 105 into a digital signal.
A signal processing unit 112 is connected to the red component A / D converter 106, the green component A / D converter 107, and the blue component A / D converter 108, and the signal processing unit 112 is white that is used for normal shooting of a color camera. It has a color adjustment function for balance adjustment, and further, a red component digital signal converted by a red component A / D converter 106, a green component A / D converter 107, and a blue component A / D converter 108, respectively. The digital signal of the green component and the digital signal of the blue component are input, and the color adjustment function for obtaining the maximum luminance difference signal according to the present invention is provided.

The color adjustment function for obtaining the maximum luminance difference signal according to the present invention and the color adjustment function for white balance adjustment used for normal photographing of the color camera are selected by the user. Since the color adjustment function for white balance adjustment used for normal photographing of the color camera is not related to the present invention, further explanation is omitted.
A red component gain control signal 109 is sent from the signal processing unit 112 to the red component amplifier 103, and the red component gain control signal 109 is used to control the gain of the red component amplifier 103.

Further, a green component amplification factor control signal 110 is sent from the signal processing unit 112 to the green component amplifier 104, and the green component amplification factor control signal 110 is used to control the amplification factor of the green component amplifier 104.
Further, a blue component amplification factor control signal 111 is sent from the signal processing unit 112 to the blue component amplifier 105, and the blue component amplification factor control signal 111 is used to control the amplification factor of the blue component amplifier 105.

The amplification factors controlled by the red component amplification factor control signal 109, the green component amplification factor control signal 110, and the blue component amplification factor control signal 111 are all set to a minimum value as an initial value, and set to a maximum value one by one.
A pixel position information signal 119 is sent from the signal processing unit 112 to the image sensor 102, and the pixel position information signal 119 is used to capture pixels from the image sensor 102.

The signal processing unit 112 is provided with a maximum luminance storage unit 113. The maximum luminance storage unit 113 stores a minimum value as an initial value, and stores a luminance of a pixel larger than the initial value as a maximum luminance when detecting a luminance signal of the pixel.
The signal processing unit 112 is provided with a minimum luminance storage unit 114. The minimum luminance storage unit 114 stores a minimum value as an initial value, and stores a luminance of a pixel larger than the initial value as a minimum luminance when detecting a luminance signal of the pixel.

Further, the signal processing unit 112 is provided with a luminance difference storage unit 115. The luminance difference storage unit 115 stores a minimum value as an initial value, and a pixel luminance difference larger than the initial value is detected as a maximum luminance difference when detecting a luminance signal of the pixel. Remember as. Here, it is assumed that pixels having a small luminance difference constitute a character 202 and a graphic 203, and pixels having a large luminance difference constitute a ground.
Further, the signal processing unit 112 is provided with a luminance signal calculation unit 116, and the luminance signal calculation unit 116 includes a red component A / D converter 106, a green component A / D converter 107, and a blue component A / D converter 108. A red component signal, a green component signal, and a blue component signal converted into a digital signal are input and calculated to detect a luminance signal.

Further, the signal processing unit 112 is provided with a maximum luminance difference acquisition color adjustment unit 117, and the maximum luminance difference acquisition color adjustment unit 117 sets only the red component amplification factor control signal 109 to the maximum value and amplifies the red component amplifier 103. Only the rate is maximized, and the maximum luminance difference acquisition operation by red component adjustment is performed on the captured pixels.
Further, the maximum luminance difference acquisition color adjusting unit 117 sets only the green component amplification factor control signal 110 to the maximum value, maximizes only the amplification factor of the green component amplifier 104, and applies the maximum luminance by the green component adjustment to the captured pixels. Perform the difference acquisition operation.

Further, the maximum luminance difference acquisition color adjustment unit 117 sets only the blue component amplification factor control signal 111 to the maximum value, maximizes the amplification factor of only the blue component amplifier 105, and sets the maximum luminance by blue component adjustment for the captured pixels. Perform the difference acquisition operation.
Further, the maximum luminance difference acquisition color adjustment unit 117 requests the image sensor 102 to capture pixels using the pixel position information signal 119.

  Further, the signal processing unit 112 is provided with a character / graphic recognition unit 118. The character / graphic recognition unit 118 replaces the luminance difference obtained in the luminance difference storage unit 115 with a character 202, a graphic having a small luminance difference. As a pixel 203, a pixel having a large luminance difference is a ground pixel, the luminance difference is binarized, and the character 202 and the graphic 203 are recognized in the same manner as the character 202 and the graphic 203 written in black on a white background. Since the recognition of the character 202 and the figure 203 is a well-known technique, the description thereof is omitted.

  FIG. 2 is a diagram illustrating an example of a photographed image photographed by the lens 101. As shown in this figure (a), in the photographed image 200, “Aiu” in blue characters 202 is written on a red background 201 of the background. As shown in FIG. It is assumed that a blue figure (barcode) 203 is written on the red ground 201. As described in the related art, the red background 201 of the photographed image 200 and the blue characters 202 and the graphic 203 have almost the same luminance, and there is no luminance difference between the two.

In this figure (a), for example, the red background 201 of the background may be red, the “eye” of the character 202 may be blue, and “c” may be green. That is, even if the color of the character 202 and the figure 203 is two colors other than the color of the ground 201, the maximum luminance difference can be obtained as will be described later with reference to FIGS. .
It should be noted that the pixels are taken from the image sensor 102 into the maximum luminance difference acquisition color adjusting unit 117 in accordance with the horizontal and vertical arrows of the captured image 200.

FIG. 3 is a diagram for explaining values set in the red component gain control signal 109, the green component gain control signal 110, and the blue component gain control signal 111 in FIG. As shown in the figure, minimum values are set as initial values for the red component gain control signal 109, the green component gain control signal 110, and the blue component gain control signal 111, respectively.
At the time of red component adjustment, a maximum value is set for the red component gain control signal 109, and a minimum initial value is set for each of the green component gain control signal 110 and the blue component gain control signal 111.

At the time of green component adjustment, a maximum value is set for the green component gain control signal 110, and a minimum initial value is set for the blue component gain control signal 111 and the red component gain control signal 109, respectively.
At the time of blue component adjustment, a maximum value is set for the blue component gain control signal 111, and a minimum initial value is set for each of the red component gain control signal 109 and the green component gain control signal 110.

FIG. 4 is a diagram for explaining the initial values of the maximum luminance storage unit 113 and the minimum luminance storage unit 114 in FIG. 1 and the magnitudes of the detected luminance signals at the time of red, green, and blue component adjustment. As shown in the figure, the initial value of the maximum luminance storage unit 113 is “a1”, and the initial value of the minimum luminance storage unit 114 is “b1”.
Furthermore, the magnitude of the detected luminance signal when the initial value (minimum value) is set for all of the red component gain control signal 109, the green component gain control signal 110, and the blue component gain control signal 111 is “c1”. To do.

Further, when adjusting the red, green, and blue components, a maximum value is set for one of the red component gain control signal 109, the green component gain control signal 110, and the blue component gain control signal 111, and the other two are set to initial values ( The magnitude of the detected luminance signal when “minimum value” is set is “d1”.
Furthermore, the initial value of the luminance difference storage unit 115 is “a1−b1”.
In this case, d1, a1, b1, and c1 have the following magnitude relationship.

d1>a1>c1> b1
a1-b1> a1-c1
5 and 6 are flowcharts for explaining an example of the maximum luminance difference acquisition operation by the red component adjustment of the maximum luminance difference acquisition color adjustment unit 117 in FIG.
As shown in FIG. 5, in step 301, the maximum luminance difference acquisition color adjusting unit 117 sets initial values (minimum values) of the red component gain control signal 109, the green component gain control signal 110, and the blue component gain control signal 111. ) And the luminance difference storage unit 115 is set to an initial value.

In step 302, the maximum luminance difference acquisition color adjustment unit 117 initializes the capture pixel position.
In step 303, i = 0 and j = 0.
In step 304, the maximum luminance difference acquisition color adjustment unit 117 sets the maximum value of the red component amplification factor control signal 109 in the red component amplifier 103.

In step 305, the maximum luminance difference acquisition color adjustment unit 117 starts adjustment of the red component amplifier 103.
In step 306, the maximum luminance difference acquisition color adjustment unit 117 sets an initial value (a 1) in the maximum luminance storage unit 113 and an initial value (b 1) in the minimum luminance storage unit 114.
In step 307, the maximum luminance difference acquisition color adjustment unit 117 captures a one-pixel luminance signal via the pixel position information signal 119.

In step 308, the maximum luminance difference acquisition color adjustment unit 117 compares the magnitude of the detected luminance signal from the luminance signal calculation unit 116 with the initial value (a1) of the maximum luminance storage unit 113. When the magnitude of the detected luminance signal is equal to or smaller than the initial value (a1) of the maximum luminance storage unit 113, the process proceeds to step 310.
In step 309, the maximum luminance difference acquisition color adjusting unit 117 determines the initial value set in the maximum luminance storage unit 113 when the magnitude of the detected luminance signal is larger than the initial value (a1) of the maximum luminance storage unit 113. (A1) is rewritten to the magnitude (d1) of the luminance signal.

In step 310, the maximum luminance difference acquisition color adjustment unit 117 compares the magnitude of the detected luminance signal from the luminance signal calculation unit 116 with the initial value (b 1) of the minimum luminance storage unit 114. When the magnitude of the detected luminance signal is equal to or larger than the initial value (b1) of the minimum luminance storage unit 114, the process proceeds to step 312.
In step 311, when the magnitude of the detected luminance signal is smaller than the initial value (b 1) of the minimum luminance storage unit 114, the maximum luminance difference acquisition color adjustment unit 117 sets the initial value set in the minimum luminance storage unit 114. (B1) is rewritten to the magnitude (c1) of the luminance signal.

  In step 312, the maximum brightness difference acquisition color adjustment unit 117 performs a calculation of the maximum brightness storage unit 113 and the minimum brightness storage unit 114 on the values stored in the maximum brightness storage unit 113 and the minimum brightness storage unit 114, thereby obtaining the brightness difference. The initial value (a1-b1) of the storage unit 115 is compared with the calculation result of the maximum luminance storage unit 113-minimum luminance storage unit 114. When the initial value (a1-b1) of the luminance difference storage unit 115 is larger than the calculation result (a1-c1) of the maximum luminance storage unit 113-minimum luminance storage unit 114, the process proceeds to step 313 and the luminance difference storage unit 115 When the initial value (a1-b1) is equal to or smaller than the calculation result (d1-b1) of the maximum luminance storage unit 113-minimum luminance storage unit 114, the process proceeds to step 314.

  In step 313, this means that the captured pixel is a green component or a blue component, and the luminance is small despite the maximum value setting of the red component gain control signal 109. That is, j means the number of pixels having a small luminance difference, and as described above, the pixels having a small luminance difference constitute the character 202 and the graphic 203. j = j + 1 is set, the number of pixels to be the green or blue character 202 and the graphic 203 is calculated, and the process proceeds to step 316.

In step 314, the maximum luminance difference acquisition color adjustment unit 117 calculates the initial value (a1-b1) set in the luminance difference storage unit 115 as the calculation result (d1-b1) of the maximum luminance storage unit 113-minimum luminance storage unit 114. Rewrite as
In step 315, this means that the captured pixel is a red component pixel, and the luminance is increased by setting the maximum value of the red component gain control signal 109. That is, i means the number of pixels having a large luminance difference, and pixels having a large luminance difference constitute the ground 201 as described above. i = i + 1 and the number of pixels that should have a red background is calculated.

In step 316, the maximum luminance difference acquisition color adjustment unit 117 determines whether or not the captured pixel is the final pixel.
In step 317, if the captured pixel is not the final pixel, the maximum brightness difference acquisition color adjustment unit 117 adds the address of the captured pixel, returns to step 306, and continues the maximum brightness difference acquisition operation for the next pixel.

As shown in FIG. 6, in step 318, the maximum luminance difference acquisition color adjustment unit 117 cancels the setting of the maximum value of the red component amplification factor control signal 109 when the captured pixel is the final pixel.
In step 319, the adjustment of the red component amplifier 103 is terminated.
In step 320, the maximum luminance difference acquisition color adjusting unit 117 calculates j / i + j and compares j / i + j with 0.001. If j / i + j is equal to or greater than 0.001, the process proceeds to step 323.

In step 321, the maximum luminance difference acquisition color adjustment unit 117 determines that the captured image 200 includes only red pixels when j / i + j is smaller than 0.001.
In step 322, the maximum luminance difference acquisition color adjustment unit 117 determines that the maximum luminance difference acquisition is impossible and ends the processing.

In step 323, the maximum luminance difference acquisition color adjustment unit 117 compares j / i + j with 0.999. If j / i + j is greater than 0.999, go to step 329.
In step 324, the maximum luminance difference acquisition color adjustment unit 117 determines that the maximum luminance difference can be acquired when j / i + j is equal to or smaller than 0.999.
In step 325, j / i + j is compared with 0.5. It is determined whether the red pixel is the ground 201 or the character 202 and the graphic 203. If j / i + j is greater than 0.5, go to step 328.

In step 326, when the maximum luminance difference acquisition color adjustment unit 117, j / i + j is equal to or smaller than 0.5, the red pixel is determined as the pixel of the background background 201.
In step 327, the maximum luminance difference acquisition color adjustment unit 117 determines that the character 202 and graphic 203 can be recognized by the character / graphic recognition unit 118. That is, as shown in (1) or (2) in FIG. 11 described later, the background 201 corresponds to red, the character 202, and the figure 203 correspond to green and blue. The brightness difference stored in the brightness difference storage unit 115 is sent to the character / graphic recognition unit 118 to cause the character / graphic recognition unit 118 to perform the recognition, so that the characters 202. Similar to the recognition of the figure 203, the recognition can be performed without reducing the recognition rate.

That is, it becomes possible to recognize the character 202 and the figure 203 written in green or blue on the background 201 having a red background. The process ends.
In step 328, in this case, it is determined that it is impossible to determine the red pixel as the background ground 201, and the process proceeds to step 331, and the next process is performed.
In step 329, the maximum luminance difference acquisition color adjustment unit 117 determines that the captured image 200 includes pixels other than red in this case.

In step 330, the maximum brightness difference acquisition color adjustment unit 117 determines that there is a possibility of acquiring the maximum brightness difference.
In step 331, the maximum luminance difference acquisition color adjustment unit 117 proceeds to FIG. 7, and performs the next color adjustment process.
7 and 8 are flowcharts for explaining an example of the maximum luminance difference acquisition operation by the green component adjustment of the maximum luminance difference acquisition color adjustment unit 117 in the continuation processing of FIGS.

As shown in FIG. 7, in step 341, following step 331 in FIG. 6, the maximum luminance difference acquisition color adjustment unit 117 sets the luminance difference storage unit 115 to an initial value.
In step 342, the maximum luminance difference acquisition color adjustment unit 117 initializes the capture pixel position.
In step 343, i = 0 and j = 0.

In step 344, the maximum luminance difference acquisition color adjustment unit 117 sets the maximum value of the green component amplification factor control signal 110 in the green component amplifier 104.
In step 345, the maximum luminance difference acquisition color adjustment unit 117 starts adjustment of the green component amplifier 104.
In step 346, the maximum luminance difference acquisition color adjustment unit 117 sets an initial value (a1) in the maximum luminance storage unit 113 and sets an initial value (b1) in the minimum luminance storage unit 114.

In step 347, the maximum luminance difference acquisition color adjustment unit 117 captures a one-pixel luminance signal via the pixel position information signal 119.
In step 348, the maximum luminance difference acquisition color adjustment unit 117 compares the magnitude of the detected luminance signal from the luminance signal calculation unit 116 with the initial value (a1) of the maximum luminance storage unit 113. When the magnitude of the detected luminance signal is equal to or smaller than the initial value (a1) of the maximum luminance storage unit 113, the process proceeds to step 350.

In step 349, when the magnitude of the detected luminance signal is larger than the initial value (a1) of the maximum luminance storage unit 113, the maximum luminance difference acquisition color adjustment unit 117 sets the initial value set in the maximum luminance storage unit 113. (A1) is rewritten to the magnitude (d1) of the luminance signal.
In step 350, the maximum luminance difference acquisition color adjustment unit 117 compares the magnitude of the detected luminance signal from the luminance signal calculation unit 116 with the initial value (b 1) of the minimum luminance storage unit 114. When the magnitude of the detected luminance signal is equal to or larger than the initial value (b1) of the minimum luminance storage unit 114, the process proceeds to step 352.

In step 351, the maximum luminance difference acquisition color adjustment unit 117 determines that the detected luminance signal is smaller than the initial value (b1) of the minimum luminance storage unit 114, the initial value set in the minimum luminance storage unit 114. (B1) is rewritten to the magnitude (c1) of the luminance signal.
In step 352, the maximum luminance difference acquisition color adjustment unit 117 performs an operation of the maximum luminance storage unit 113 -minimum luminance storage unit 114 on the values stored in the maximum luminance storage unit 113 and the minimum luminance storage unit 114, thereby calculating the luminance difference. The initial value (a1-b1) of the storage unit 115 is compared with the calculation result of the maximum luminance storage unit 113-minimum luminance storage unit 114. When the initial value (a1-b1) of the luminance difference storage unit 115 is larger than the calculation result (a1-c1) of the maximum luminance storage unit 113-minimum luminance storage unit 114, the process proceeds to step 353 and the luminance difference storage unit 115 When the initial value (a1-b1) is equal to or smaller than the calculation result (d1-b1) of the maximum luminance storage unit 113-minimum luminance storage unit 114, the process proceeds to step 354.

  In step 353, this means that the captured pixel is a blue component or a red component, and the luminance is small despite the maximum value setting of the green component gain control signal 110. That is, j means the number of pixels having a small luminance difference, and as described above, the pixels having a small luminance difference constitute the character 202 and the graphic 203. j = j + 1 is set, the number of pixels to be blue or red character 202 and graphic 203 is calculated, and the process proceeds to step 356.

In step 354, the maximum luminance difference acquisition color adjusting unit 117 calculates the initial value (a1-b1) set in the luminance difference storage unit 115 as the calculation result (d1-b1) of the maximum luminance storage unit 113-minimum luminance storage unit 114. Rewrite as
In step 355, in this case, the captured pixel is a green component pixel, which means that the luminance is increased by setting the maximum value of the green component amplification factor control signal 110. That is, i means the number of pixels having a large luminance difference, and pixels having a large luminance difference constitute the ground 201 as described above. The number of pixels that should be i = i + 1 and the background 201 having a green background is calculated.

In step 356, the maximum luminance difference acquisition color adjustment unit 117 determines whether or not the captured pixel is the final pixel.
In step 357, if the captured pixel is not the final pixel, the maximum brightness difference acquisition color adjustment unit 117 adds the address of the captured pixel, returns to step 346, and continues the maximum brightness difference acquisition operation for the next pixel.

As shown in FIG. 8, in step 358, the maximum luminance difference acquisition color adjustment unit 117 cancels the maximum value setting of the green component amplification factor control signal 110 when the captured pixel is the final pixel.
In step 359, the adjustment of the green component amplifier 104 is terminated.
In step 360, the maximum luminance difference acquisition color adjustment unit 117 calculates j / i + j and compares j / i + j with 0.001. If j / i + j is equal to or greater than 0.001, the process proceeds to step 363.

In step 361, the maximum luminance difference acquisition color adjustment unit 117 determines that the captured image 200 includes only green pixels when j / i + j is smaller than 0.001.
In step 362, the maximum brightness difference acquisition color adjustment unit 117 determines that the maximum brightness difference cannot be acquired and ends the process.

In step 363, the maximum luminance difference acquisition color adjustment unit 117 compares j / i + j with 0.999. If j / i + j is greater than 0.999, go to step 369.
In step 364, the maximum luminance difference acquisition color adjustment unit 117 determines that the maximum luminance difference can be acquired when j / i + j is equal to or smaller than 0.999.
In step 365, j / i + j is compared with 0.5. It is determined whether the green pixel becomes the ground 201 or the character 202 and the graphic 203. If j / i + j is greater than 0.5, go to step 368.

In step 366, when the maximum luminance difference acquisition color adjustment unit 117, j / i + j is equal to or smaller than 0.5, the green pixel is determined as the pixel of the background background 201.
In step 367, the maximum luminance difference acquisition color adjustment unit 117 determines that the character 202 and graphic 203 can be recognized by the character / graphic recognition unit 118. That is, as shown in (3) or (4) in FIG. 11 described later, the background 201 corresponds to green, the character 202, and the figure 203 correspond to blue and red. The brightness difference in the brightness difference storage unit 115 is sent to the character / graphic recognition unit 118 to cause the character / graphic recognition unit 118 to perform recognition, and the character 202 written in black on a white background as in the past, Similar to the recognition of the figure 203, the recognition can be performed without reducing the recognition rate.

That is, it becomes possible to recognize the character 202 and the figure 203 written in blue or red on the ground 201 having a green background. The process ends.
In step 368, in this case, it is determined that it is impossible to determine the green pixel as the background ground 201, the process proceeds to step 371, and the next process is performed.
In step 369, the maximum luminance difference acquisition color adjustment unit 117 determines that the captured image 200 is composed of pixels other than red and green in this case.

In step 370, the maximum brightness difference acquisition color adjustment unit 117 determines that there is a possibility of acquiring the maximum brightness difference.
In step 371, the maximum luminance difference acquisition color adjustment unit 117 proceeds to FIG. 9 and performs the next color adjustment process.
FIGS. 9 and 10 are flowcharts for explaining an example of the maximum luminance difference acquisition operation by the blue component adjustment of the maximum luminance difference acquisition color adjustment unit 117 in the continuation processing of FIGS.

As shown in FIG. 9, in step 381, following step 371 in FIG. 8, the maximum luminance difference acquisition color adjustment unit 117 sets the luminance difference storage unit 115 to an initial value.
In step 382, the maximum luminance difference acquisition color adjustment unit 117 initializes the capture pixel position.
In step 383, i = 0 and j = 0.

In step 384, the maximum luminance difference acquisition color adjustment unit 117 sets the maximum value of the blue component amplification factor control signal 111 in the blue component amplifier 105.
In step 385, the maximum luminance difference acquisition color adjustment unit 117 starts adjustment of the blue component amplifier 105.
In step 386, the maximum luminance difference acquisition color adjustment unit 117 sets an initial value (a1) in the maximum luminance storage unit 113 and sets an initial value (b1) in the minimum luminance storage unit 114.

In step 387, the maximum luminance difference acquisition color adjustment unit 117 captures a one-pixel luminance signal via the pixel position information signal 119.
In step 388, the maximum luminance difference acquisition color adjustment unit 117 compares the magnitude of the detected luminance signal from the luminance signal calculation unit 116 with the initial value (a1) of the maximum luminance storage unit 113. When the magnitude of the detected luminance signal is equal to or smaller than the initial value (a1) of the maximum luminance storage unit 113, the process proceeds to step 390.

In step 389, when the magnitude of the detected luminance signal is larger than the initial value (a1) of the maximum luminance storage unit 113, the maximum luminance difference acquisition color adjustment unit 117 sets the initial value set in the maximum luminance storage unit 113. (A1) is rewritten to the magnitude (d1) of the luminance signal.
In step 390, the maximum luminance difference acquisition color adjustment unit 117 compares the magnitude of the detected luminance signal from the luminance signal calculation unit 116 with the initial value (b1) of the minimum luminance storage unit 114. When the magnitude of the detected luminance signal is equal to or larger than the initial value (b1) of the minimum luminance storage unit 114, the process proceeds to step 392.

In step 391, when the magnitude of the detected luminance signal is smaller than the initial value (b1) of the minimum luminance storage unit 114, the maximum luminance difference acquisition color adjustment unit 117 sets the initial value set in the minimum luminance storage unit 114. (B1) is rewritten to the magnitude (c1) of the luminance signal.
In step 392, the maximum luminance difference acquisition color adjustment unit 117 performs an operation of the maximum luminance storage unit 113 -minimum luminance storage unit 114 on the values stored in the maximum luminance storage unit 113 and the minimum luminance storage unit 114, thereby calculating the luminance difference. The initial value (a1-b1) of the storage unit 115 is compared with the calculation result of the maximum luminance storage unit 113-minimum luminance storage unit 114. When the initial value (a1-b1) of the luminance difference storage unit 115 is larger than the calculation result (a1-c1) of the maximum luminance storage unit 113-minimum luminance storage unit 114, the process proceeds to step 393, where the luminance difference storage unit 115 When the initial value (a1-b1) is equal to or smaller than the calculation result (d1-b1) of the maximum luminance storage unit 113-minimum luminance storage unit 114, the process proceeds to step 394.

  In step 393, this means that the captured pixel is a red component or a green component, and the luminance is small despite the maximum value setting of the blue component amplification factor control signal 111. That is, j means the number of pixels having a small luminance difference, and as described above, the pixels having a small luminance difference constitute the character 202 and the graphic 203. j = j + 1 is set, the number of pixels to be red or green character 202 and graphic 203 is calculated, and the process proceeds to step 396.

In step 394, the maximum luminance difference acquisition color adjustment unit 117 calculates the initial value (a1-b1) set in the luminance difference storage unit 115 as the calculation result (d1-b1) of the maximum luminance storage unit 113-minimum luminance storage unit 114. Rewrite as
In step 395, this means that the captured pixel is a blue component and the luminance is increased by setting the maximum value of the blue component amplification factor control signal 111. That is, i means the number of pixels having a large luminance difference, and pixels having a large luminance difference constitute the ground 201 as described above. The number of pixels that should be i = i + 1 and the background 201 of the blue background is calculated.

In step 396, the maximum luminance difference acquisition color adjustment unit 117 determines whether or not the captured pixel is the final pixel.
In step 397, if the captured pixel is not the final pixel, the maximum brightness difference acquisition color adjustment unit 117 adds the address of the captured pixel, returns to step 386, and continues the maximum brightness difference acquisition operation for the next pixel.

As shown in FIG. 10, in step 398, the maximum luminance difference acquisition color adjusting unit 117 cancels the maximum value setting of the blue component amplification factor control signal 111 when the captured pixel is the final pixel.
In step 399, the adjustment of the blue component amplifier 105 is finished.
In step 400, the maximum luminance difference acquisition color adjustment unit 117 calculates j / i + j and compares j / i + j with 0.001. If j / i + j is equal to or greater than 0.001, the process proceeds to step 403.

In step 401, the maximum luminance difference acquisition color adjustment unit 117 determines that the captured image 200 includes only blue pixels when j / i + j is smaller than 0.001.
In step 402, the maximum brightness difference acquisition color adjustment unit 117 determines that the maximum brightness difference cannot be acquired and ends the process.

In step 403, in this case, the maximum luminance difference acquisition color adjustment unit 117 determines that the maximum luminance difference can be acquired.
In step 404, the maximum luminance difference acquisition color adjustment unit 117 determines the blue pixel as the pixel of the background background 201.

  In step 405, the maximum luminance difference acquisition color adjustment unit 117 determines that the character / graphic recognition unit 118 can recognize the character 202 and the graphic 203. That is, as shown in (5) or (6) in FIG. 11 described later, the background 201 corresponds to blue, the character 202, and the figure 203 correspond to red and green. The brightness difference in the brightness difference storage unit 115 is sent to the character / graphic recognition unit 118 to cause the character / graphic recognition unit 118 to perform recognition, and the character 202 written in black on a white background as in the past, Similar to the recognition of the figure 203, the recognition can be performed without reducing the recognition rate.

That is, the character 202 and the figure 203 written in red or green on the blue background 201 can be recognized. The process ends.
In the above description, the maximum of red component amplifier 103, green component amplifier 104, and blue component amplifier 105 in the order of red component gain control signal 109, green component gain control signal 110, and blue component gain control signal 111 is the maximum. Although the amplification factor is set, this order is merely an example, and the order is not limited to this. Other orders may be used. The same applies hereinafter.

Further, in step 320 in FIG. 6, step 360 in FIG. 8, and step 400 in FIG. 10, j / i + j is compared with 0.001, but the comparison target “0.001” is an example. A numerical value optimal for the recognition of the character 202 and the graphic 203 by the character / graphic recognition unit 118 is selected. The same applies hereinafter.
Further, j / i + j and 0.999 are compared in step 323 in FIG. 6 and step 363 in FIG. 8, but “0.999”, which is the object of comparison, is an example, and the character / graphic recognition unit 118. The optimal numerical value for the recognition of the character 202 and the figure 203 is selected. The same applies hereinafter.

Furthermore, in the above description, the brightness of the ground 201 is greater than the brightness of the character 202 and the graphic 203, but may be reversed. This is because the character / figure recognition unit 118 may decide either one. The same applies hereinafter.
FIG. 11 is a diagram illustrating a combination of the three primary colors red, green, and blue of the ground 201 of the photographed image 200, the character 202, and the figure 203 in FIG. As an example of a combination of the color of the background ground 201, the character 202, and the graphic 203 in the photographed image 200, the red color of the ground 201 corresponds to the green or blue color of the character 202 and the graphic 203 as shown in FIG. The green color of the ground 201 corresponds to the character 202 and the blue or red color of the graphic 203, and the blue color of the ground 201 corresponds to the red or green color of the character 202 and the graphic 203.

As described above, in order to obtain the maximum luminance difference with respect to the combination of (1) and (2) in FIG. 11, the processing in FIGS. 5 and 6 is necessary, and (3) in FIG. In order to obtain the maximum luminance difference for the combination of (4), the processing of FIG. 5, FIG. 6 → FIG. 7, and FIG. 8 is necessary, and the combination of (5) and (6) of FIG. On the other hand, in order to obtain the maximum luminance difference, the processes in FIGS. 5, 6 → 7, 8 → 9, and 10 are required.
As shown in FIG. 5B, the red color of the background 201 corresponds to the characters 202 and 203 of the figure 203, and the green color of the background 201 corresponds to the characters 202 and the blue and red colors of the figure 203. The blue color may be a combination of the letters 202 and the red and green colors of the figure 203. Even in this case, the maximum luminance difference can be obtained. It becomes possible to increase the number of combinations of the ground 201, the character 202, and the figure 203.

  Therefore, according to the present invention, the amplification factors of the red component, the green component, and the blue component with the amplification factor set to the minimum are sequentially maximized, for example, characters written in blue on the red background 201 of the background. For 202 and figure 203, the amplification factor of the red component amplifier is maximized to maximize the luminance difference of the pixels of red background 201 of the background, and the luminance difference of the pixels of characters 202 and figure 203 written in blue is Since the color adjustment that minimizes the color adjustment is performed, the character 202 and the graphic 203 are not reduced without reducing the recognition rate as in the case of the recognition of the character 202 and the graphic 203 written in black on a white background. Can be recognized.

  FIG. 12 is a block diagram showing a schematic configuration of a color adjustment system of a color camera when the amplification factor of one amplifier is fixed to the minimum in the first modification of FIG. As shown in this figure, compared with FIG. 1, as an example, the amplification factors of the red component amplifier 103 and the blue component amplifier 105 can be adjusted, and the amplification factor of the green component amplifier 104 is fixed. That is, the red component amplification factor control signal 109 and the blue component amplification factor control signal 111 control the amplification factors of the red component amplifier 103 and the blue component amplifier 105, respectively.

Since the above example is an example, any one of the red component amplifier 103, the green component amplifier 104, and the blue component amplifier 105 may fix the amplification factor.
Further, the signal processing unit 112 is provided with a luminance difference inversion unit 120, and the luminance difference inversion unit 120 has a function of inverting the luminance difference in the minimum luminance storage unit 114.
Even in this case, for example, with respect to the blue character 202 and the graphic 203 on the red background 201 of the background, the luminance of the pixel of the red background 201 of the background is maximized, and the character 202 and the graphic 203 written in blue are maximized. It is possible to minimize the luminance of the pixels as follows.

FIGS. 13 and 14 are flowcharts for explaining an operation example in which one amplification factor is fixed by acquiring the maximum luminance difference by the red component adjustment of the maximum luminance difference acquiring color adjusting unit 117 in FIG.
As shown in FIG. 13, in step 421, the maximum luminance difference acquisition color adjusting unit 117 sets the red component amplification factor control signal 109 and the green component amplification factor control signal 110 to initial values (minimum values), respectively. The storage unit 115 is set to an initial value.

In step 422, the maximum luminance difference acquisition color adjustment unit 117 initializes the capture pixel position.
In step 423, i = 0 and j = 0.
In step 424, the maximum luminance difference acquisition color adjustment unit 117 sets the maximum value of the red component amplification factor control signal 109 in the red component amplifier 103.

In step 425, the maximum luminance difference acquisition color adjustment unit 117 starts adjustment of the red component amplifier 103.
In step 426, the maximum luminance difference acquisition color adjustment unit 117 sets an initial value (a 1) in the maximum luminance storage unit 113 and an initial value (b 1) in the minimum luminance storage unit 114.
In step 427, the maximum luminance difference acquisition color adjustment unit 117 captures a one-pixel luminance signal via the pixel position information signal 119.

In step 428, the maximum luminance difference acquisition color adjustment unit 117 compares the magnitude of the detected luminance signal from the luminance signal calculation unit 116 with the initial value (a 1) of the maximum luminance storage unit 113. When the magnitude of the detected luminance signal is equal to or smaller than the initial value (a1) of the maximum luminance storage unit 113, the process proceeds to step 430.
In step 429, the maximum luminance difference acquisition color adjusting unit 117 determines that the detected luminance signal is larger than the initial value (a1) of the maximum luminance storage unit 113, the initial value set in the maximum luminance storage unit 113. (A1) is rewritten to the magnitude (d1) of the luminance signal.

In step 430, the maximum luminance difference acquisition color adjustment unit 117 compares the magnitude of the detected luminance signal from the luminance signal calculation unit 116 with the initial value (b1) of the minimum luminance storage unit 114. When the magnitude of the detected luminance signal is equal to or larger than the initial value (b1) of the minimum luminance storage unit 114, the process proceeds to step 432.
In step 431, the maximum luminance difference acquisition color adjustment unit 117 sets the initial value set in the minimum luminance storage unit 114 when the magnitude of the detected luminance signal is smaller than the initial value (b1) of the minimum luminance storage unit 114. (B1) is rewritten to the magnitude (c1) of the luminance signal.

  In step 432, the maximum luminance difference acquisition color adjustment unit 117 calculates the maximum luminance storage unit 113 and the minimum luminance storage unit 114 for the values stored in the maximum luminance storage unit 113 and the minimum luminance storage unit 114, thereby calculating the luminance difference. The initial value (a1-b1) of the storage unit 115 is compared with the calculation result of the maximum luminance storage unit 113-minimum luminance storage unit 114. When the initial value (a1-b1) of the luminance difference storage unit 115 is larger than the calculation result (a1-c1) of the maximum luminance storage unit 113-minimum luminance storage unit 114, the process proceeds to step 433, and the luminance difference storage unit 115 When the initial value (a1-b1) is equal to or smaller than the calculation result (d1-b1) of the maximum luminance storage unit 113-minimum luminance storage unit 114, the process proceeds to step 434.

  In step 433, this means that the captured pixel is a green component or a blue component, and the luminance is small despite the maximum value setting of the red component gain control signal 109. That is, j means the number of pixels having a small luminance difference, and as described above, the pixels having a small luminance difference constitute the character 202 and the graphic 203. j = j + 1 is set, the number of pixels to be the green or blue character 202 and the graphic 203 is calculated, and the process proceeds to Step 436.

In step 434, the maximum luminance difference acquisition color adjustment unit 117 calculates the initial value (a1-b1) set in the luminance difference storage unit 115 as the calculation result (d1-b1) of the maximum luminance storage unit 113-minimum luminance storage unit 114. Rewrite as
In step 435, in this case, the captured pixel is a red component pixel, which means that the luminance is increased by setting the maximum value of the red component amplification factor control signal 109. That is, i means the number of pixels having a large luminance difference, and pixels having a large luminance difference constitute the ground 201 as described above. The number of pixels that should be i = i + 1 and the background 201 having a red background is calculated.

In step 436, the maximum luminance difference acquisition color adjustment unit 117 determines whether or not the captured pixel is the final pixel.
In step 437, if the acquired pixel is not the final pixel, the maximum luminance difference acquisition color adjustment unit 117 adds the address of the acquired pixel, returns to step 426, and continues the maximum luminance difference acquisition operation for the next pixel.

As shown in FIG. 14, in step 438, the maximum luminance difference acquisition color adjusting unit 117 cancels the setting of the maximum value of the red component amplification factor control signal 109 when the captured pixel is the final pixel.
In step 439, the adjustment of the red component amplifier 103 is terminated.
In step 440, the maximum luminance difference acquisition color adjustment unit 117 calculates j / i + j and compares j / i + j with 0.001. If j / i + j is equal to or greater than 0.001, the process proceeds to step 443.

In step 441, the maximum luminance difference acquisition color adjustment unit 117 determines that the photographed image 200 includes only red pixels when j / i + j is smaller than 0.001.
In step 442, the maximum brightness difference acquisition color adjustment unit 117 determines that the maximum brightness difference cannot be acquired and ends the process.

In step 443, the maximum luminance difference acquisition color adjustment unit 117 compares j / i + j with 0.999. If j / i + j is greater than 0.999, go to step 450.
In step 444, the maximum luminance difference acquisition color adjustment unit 117 determines that the maximum luminance difference can be acquired when j / i + j is equal to or smaller than 0.999.
In step 445, j / i + j is compared with 0.5. It is determined whether the red pixel is the ground 201 or the character 202 and the graphic 203. If j / i + j is greater than 0.5, go to step 448.

In step 446, when the maximum luminance difference acquisition color adjusting unit 117, j / i + j is equal to or smaller than 0.5, the red pixel is determined as the pixel of the background background 201.
In step 447, the maximum luminance difference acquisition color adjustment unit 117 determines that the character 202 and graphic 203 can be recognized by the character / graphic recognition unit 118. That is, as shown in (1) or (2) in FIG. 17 described later, the background 201 corresponds to red, the character 202, and the figure 203 correspond to green and blue. The brightness difference in the brightness difference storage unit 115 is sent to the character / graphic recognition unit 118 to cause the character / graphic recognition unit 118 to perform recognition, and the character 202 written in black on a white background as in the past, Similar to the recognition of the figure 203, the recognition can be performed without reducing the recognition rate.

That is, it becomes possible to recognize the character 202 and the figure 203 written in green or blue on the background 201 having a red background. The process ends.
In step 448, in this case, the maximum luminance difference acquisition color adjustment unit 117 inverts the luminance difference data stored in the luminance difference storage unit 115 with respect to the luminance difference inversion unit 120.
In step 449, the maximum luminance difference acquisition color adjustment unit 117 determines the red pixel as the pixel of the character 202 and the graphic 203 for the inverted luminance difference of the luminance difference storage unit 115, and the character / graphic recognition unit 118. Thus, it is determined that the character 202 and the figure 203 can be recognized. Proceed to step 487. That is, as shown in (4) or (5) in FIG. 17 described later, the background 201 corresponds to green or blue, the character 202, and the figure 203 correspond to red. The brightness difference in the brightness difference storage unit 115 is sent to the character / graphic recognition unit 118 to cause the character / graphic recognition unit 118 to perform recognition, and the character 202 written in black on a white background as in the past, Similar to the recognition of the figure 203, the recognition can be performed without reducing the recognition rate.

In step 450, the maximum luminance difference acquisition color adjustment unit 117 determines that the captured image 200 is composed of pixels other than red in this case.
In step 451, the maximum luminance difference acquisition color adjustment unit 117 determines that there is a possibility of acquiring the maximum luminance difference.
In step 452, the maximum luminance difference acquisition color adjustment unit 117 proceeds to FIG. 15, and performs the next color adjustment process.

FIGS. 15 and 16 are flowcharts for explaining an operation example in which one amplification factor is fixed by the maximum luminance difference acquisition by blue component adjustment of the maximum luminance difference acquisition color adjustment unit 117 in the continuation processing of FIGS. 13 and 14.
As shown in FIG. 15, in step 461, the maximum luminance difference acquisition color adjustment unit 117 sets the luminance difference storage unit 115 to an initial value.
In step 462, the maximum luminance difference acquisition color adjustment unit 117 initializes the capture pixel position.

In step 463, i = 0 and j = 0.
In step 464, the maximum luminance difference acquisition color adjustment unit 117 sets the maximum value of the blue component amplification factor control signal 111 in the blue component amplifier 105.
In step 465, the maximum luminance difference acquisition color adjustment unit 117 starts adjustment of the blue component amplifier 105.

In step 466, the maximum luminance difference acquisition color adjustment unit 117 sets an initial value (a1) in the maximum luminance storage unit 113 and sets an initial value (b1) in the minimum luminance storage unit 114.
In step 467, the maximum luminance difference acquisition color adjustment unit 117 captures the one-pixel luminance signal via the pixel position information signal 119.
In step 468, the maximum luminance difference acquisition color adjustment unit 117 compares the magnitude of the detected luminance signal from the luminance signal calculation unit 116 with the initial value (a1) of the maximum luminance storage unit 113. When the magnitude of the detected luminance signal is equal to or smaller than the initial value (a1) of the maximum luminance storage unit 113, the process proceeds to step 470.

In step 469, when the magnitude of the detected luminance signal is larger than the initial value (a1) of the maximum luminance storage unit 113, the maximum luminance difference acquisition color adjustment unit 117 sets the initial value set in the maximum luminance storage unit 113. (A1) is rewritten to the magnitude (d1) of the luminance signal.
In step 470, the maximum luminance difference acquisition color adjustment unit 117 compares the magnitude of the detected luminance signal from the luminance signal calculation unit 116 with the initial value (b1) of the minimum luminance storage unit 114. When the magnitude of the detected luminance signal is equal to or larger than the initial value (b1) of the minimum luminance storage unit 114, the process proceeds to step 472.

In step 471, the maximum luminance difference acquisition color adjustment unit 117 determines the initial value set in the minimum luminance storage unit 114 when the magnitude of the detected luminance signal is smaller than the initial value (b1) of the minimum luminance storage unit 114. (B1) is rewritten to the magnitude (c1) of the luminance signal.
In step 472, the maximum luminance difference acquisition color adjustment unit 117 performs an operation of the maximum luminance storage unit 113 -minimum luminance storage unit 114 on the values stored in the maximum luminance storage unit 113 and the minimum luminance storage unit 114 to obtain the luminance difference. The initial value (a1-b1) of the storage unit 115 is compared with the calculation result of the maximum luminance storage unit 113-minimum luminance storage unit 114. When the initial value (a1-b1) of the luminance difference storage unit 115 is larger than the calculation result (a1-c1) of the maximum luminance storage unit 113-minimum luminance storage unit 114, the process proceeds to step 473 and the luminance difference storage unit 115 When the initial value (a1-b1) is equal to or smaller than the calculation result (d1-b1) of the maximum luminance storage unit 113-minimum luminance storage unit 114, the process proceeds to step 474.

  In step 473, this means that the captured pixel is a red component or green component pixel, and the luminance is small despite the maximum value setting of the blue component amplification factor control signal 111. That is, j means the number of pixels having a small luminance difference, and as described above, the pixels having a small luminance difference constitute the character 202 and the graphic 203. j = j + 1 is set, the number of pixels to be red or green character 202 and graphic 203 is calculated, and the process proceeds to step 476.

In step 474, the maximum luminance difference acquisition color adjustment unit 117 calculates the initial value (a1-b1) set in the luminance difference storage unit 115 as the calculation result (d1-b1) of the maximum luminance storage unit 113-minimum luminance storage unit 114. Rewrite as
In step 475, this means that the captured pixel is a blue component pixel and the luminance is increased by setting the maximum value of the blue component amplification factor control signal 111. That is, i means the number of pixels having a large luminance difference, and pixels having a large luminance difference constitute the ground 201 as described above. The number of pixels that should be i = i + 1 and the background 201 of the blue background is calculated.

In step 476, the maximum luminance difference acquisition color adjustment unit 117 determines whether or not the captured pixel is the final pixel.
In step 477, if the captured pixel is not the final pixel, the maximum brightness difference acquisition color adjustment unit 117 adds the address of the captured pixel, returns to step 466, and continues the maximum brightness difference acquisition operation for the next pixel.

As shown in FIG. 16, in step 478, the maximum luminance difference acquisition color adjusting unit 117 cancels the maximum value setting of the blue component amplification factor control signal 111 when the captured pixel is the final pixel.
In step 479, the adjustment of the blue component amplifier 105 is finished.
In step 480, the maximum luminance difference acquisition color adjustment unit 117 calculates j / i + j and compares j / i + j with 0.001. If j / i + j is equal to or greater than 0.001, the process proceeds to step 483.

In step 481, the maximum luminance difference acquisition color adjustment unit 117 determines that the photographed image 200 includes only blue pixels when j / i + j is smaller than 0.001.
In step 482, the maximum brightness difference acquisition color adjustment unit 117 determines that the maximum brightness difference cannot be acquired and ends the process.
In step 483, in this case, the maximum luminance difference acquisition color adjustment unit 117 determines that the maximum luminance difference can be acquired.

In step 484, j / i + j is compared with 0.5. It is determined whether the blue pixel is the ground 201 or the character 202 and the graphic 203. If j / i + j is greater than 0.5, go to step 487.
In step 485, the maximum luminance difference acquisition color adjusting unit 117 determines the blue pixel as the pixel of the background ground 201 when j / i + j is equal to or smaller than 0.5.

  In step 486, the maximum luminance difference acquisition color adjusting unit 117 determines that the character 202 and graphic 203 can be recognized by the character / graphic recognition unit 118. That is, as shown in (6) in FIG. 17 described later, the background 201 corresponds to blue, the character 202, and the figure 203 correspond to green. The brightness difference in the brightness difference storage unit 115 is sent to the character / graphic recognition unit 118 to cause the character / graphic recognition unit 118 to perform recognition, and the character 202 written in black on a white background as in the past, Similar to the recognition of the figure 203, the recognition can be performed without reducing the recognition rate.

That is, it becomes possible to recognize the character 202 and the figure 203 written in green on the background 201 with a blue background. The process ends.
In step 487, in this case, the maximum luminance difference acquisition color adjustment unit 117 inverts the luminance difference data stored in the luminance difference storage unit 115 with respect to the luminance difference inversion unit 120.
In step 488, the maximum luminance difference acquisition color adjustment unit 117 determines the blue pixel as the pixel of the character 202 and the graphic 203 for the inverted luminance difference of the luminance difference storage unit 115, and the character / graphic recognition unit 118. Thus, it is determined that the character 202 and the figure 203 can be recognized. Proceed to step 488. That is, as shown in (3) in FIG. 17 described later, the background 201 corresponds to green, the character 202, and the figure 203 correspond to blue. The brightness difference in the brightness difference storage unit 115 is sent to the character / graphic recognition unit 118 to cause the character / graphic recognition unit 118 to perform recognition, and the character 202 written in black on a white background as in the past, Similar to the recognition of the figure 203, the recognition can be performed without reducing the recognition rate.
That is, it becomes possible to recognize the character 202 and the graphic 203 written in blue on the ground 201 having a green background.

In the description of FIGS. 13-16 above, the maximum amplification factor is set for the red component amplifier 103 and the blue component amplifier 105 in the order of the red component amplification factor control signal 109 and the blue component amplification factor control signal 111. This order is an example and may be reversed.
FIG. 17 is a combination of the color of the ground 201 of the photographed image 200 and the character 202 and the graphic 203 based on the example of the maximum brightness difference acquisition operation of the maximum brightness difference acquisition color adjusting unit 117 of FIGS. FIG.

The luminance difference inversion unit 120 is provided so that the pixels having the maximum luminance difference and the minimum luminance difference are mutually inverted so that the combination shown in FIG. 11 can be realized.
In order to obtain the maximum luminance difference, as described above, the processing in FIGS. 13 and 14, the processing in FIGS. 13 and 14 (inversion: see steps 448 and 449), FIG. 13, FIG. 14 to FIG. The processing of FIG. 16 and the processing of FIG. 13, FIG. 14 → FIG. 15, and FIG. 16 (inversion: see steps 487 and 488) are necessary.

  Therefore, according to the present invention, the amplification factor of the green component amplifier 104 is fixed, and the amplification factors of the red component amplifier 103 and the blue component amplifier 105 are made variable. It is possible to maximize the luminance of the pixels of the red background 201 of the background for the 202 and the graphic 203 and to minimize the luminance of the pixels of the character 202 and the graphic 203 written in blue.

In the configuration example of FIG. 12, the amplification factor of the green component amplifier 104 is fixed, and in the examples of FIGS. 13 to 16, the amplification factors of the red component amplifier 103 and the blue component amplifier 105 are made variable, but this example is an example. It is possible to obtain the same effect by fixing any one of the red component amplifier 103, the green component amplifier 104, and the blue component amplifier 105 and making the other two variable.
Therefore, according to the present invention, the amplification factor of any one of the red, green, and blue component amplifiers whose amplification factors are set to the minimum is fixed to the minimum, and the other two are alternately maximized to amplify. For example, for the character 202 and the figure 203 written in blue on the red background 201 of the background, for example, the red component amplifier The color difference is adjusted so as to minimize the luminance difference between the pixels of the character 202 and the graphic 203 written in blue. For the character 202 and the graphic 203 written in blue on the red background 201, when the amplification factor of the blue component amplifier is maximized, the obtained luminance difference is inverted, so that And characters written in black on a white background 02, without lowering the recognition as well as recognition rate of a graphic 203, character 202, it is possible to recognize the figure 203.

The above description has been given for the three primary colors of red, green, and blue. Further, the acquisition of the maximum luminance difference when yellow, cyan, and magenta are added as intermediate colors will be described using the configuration of FIG.
18 and 19 are flowcharts for explaining an operation example in which intermediate colors are added in the maximum luminance difference acquisition by the red component adjustment of the maximum luminance difference acquisition color adjustment unit 117 in FIG.

As shown in FIG. 18, in step 501, the maximum luminance difference acquisition color adjusting unit 117 sets initial values (minimum values) of the red component gain control signal 109, the green component gain control signal 110, and the blue component gain control signal 111. ) And the luminance difference storage unit 115 is set to an initial value.
In step 502, the maximum luminance difference acquisition color adjustment unit 117 initializes the capture pixel position.

In step 503, i = 0 and j = 0.
In step 504, the maximum luminance difference acquisition color adjustment unit 117 sets the maximum value of the red component amplification factor control signal 109 in the red component amplifier 103.
In step 505, the maximum luminance difference acquisition color adjustment unit 117 starts adjustment of the red component amplifier 103.

In step 506, the maximum luminance difference acquisition color adjustment unit 117 sets an initial value (a1) in the maximum luminance storage unit 113 and sets an initial value (b1) in the minimum luminance storage unit 114.
In step 507, the maximum luminance difference acquisition color adjustment unit 117 captures a one-pixel luminance signal via the pixel position information signal 119.
In step 508, the maximum luminance difference acquisition color adjustment unit 117 compares the magnitude of the detected luminance signal from the luminance signal calculation unit 116 with the initial value (a1) of the maximum luminance storage unit 113. When the magnitude of the detected luminance signal is equal to or smaller than the initial value (a1) of the maximum luminance storage unit 113, the process proceeds to step 510.

In step 509, the maximum luminance difference acquisition color adjustment unit 117 determines that the detected luminance signal is larger than the initial value (a1) of the maximum luminance storage unit 113, the initial value set in the maximum luminance storage unit 113. (A1) is rewritten to the magnitude (d1) of the luminance signal.
In step 510, the maximum luminance difference acquisition color adjustment unit 117 compares the magnitude of the detected luminance signal from the luminance signal calculation unit 116 with the initial value (b1) of the minimum luminance storage unit 114. When the magnitude of the detected luminance signal is equal to or larger than the initial value (b1) of the minimum luminance storage unit 114, the process proceeds to step 512.

In step 511, the maximum luminance difference acquisition color adjustment unit 117 determines the initial value set in the minimum luminance storage unit 114 when the magnitude of the detected luminance signal is smaller than the initial value (b1) of the minimum luminance storage unit 114. (B1) is rewritten to the magnitude (c1) of the luminance signal.
In step 512, the maximum luminance difference acquisition color adjustment unit 117 performs an operation of the maximum luminance storage unit 113 -minimum luminance storage unit 114 on the values stored in the maximum luminance storage unit 113 and the minimum luminance storage unit 114, thereby calculating the luminance difference. The initial value (a1-b1) of the storage unit 115 is compared with the calculation result of the maximum luminance storage unit 113-minimum luminance storage unit 114. When the initial value (a1-b1) of the luminance difference storage unit 115 is larger than the calculation result (a1-c1) of the maximum luminance storage unit 113-minimum luminance storage unit 114, the process proceeds to step 513 and the luminance difference storage unit 115 When the initial value (a1-b1) is equal to or smaller than the calculation result (d1-b1) of the maximum luminance storage unit 113-minimum luminance storage unit 114, the process proceeds to step 514.

  In step 513, in this case, it means that the luminance of the captured pixel is small despite the maximum value setting of the red component amplification factor control signal 109. That is, j means the number of pixels having a small luminance difference, and as described above, the pixels having a small luminance difference constitute the character 202 and the graphic 203. j = j + 1 is set, the number of pixels to be the character 202 and the graphic 203 is calculated, and the process proceeds to Step 516.

In step 514, the maximum luminance difference acquisition color adjustment unit 117 calculates the initial value (a1-b1) set in the luminance difference storage unit 115 as the calculation result (d1-b1) of the maximum luminance storage unit 113-minimum luminance storage unit 114. Rewrite as
In step 515, in this case, it means that the luminance of the captured pixel is increased by setting the maximum value of the red component gain control signal 109. That is, i means the number of pixels having a large luminance difference, and pixels having a large luminance difference constitute the ground 201 as described above. i = i + 1 and the number of pixels to be the background 201 is calculated.

In step 516, the maximum luminance difference acquisition color adjustment unit 117 determines whether or not the captured pixel is the final pixel.
In step 517, if the captured pixel is not the final pixel, the maximum brightness difference acquisition color adjustment unit 117 adds the address of the captured pixel, returns to step 506, and continues the maximum brightness difference acquisition operation for the next pixel.

As shown in FIG. 19, in step 518, the maximum luminance difference acquisition color adjustment unit 117 cancels the setting of the maximum value of the red component amplification factor control signal 109 when the captured pixel is the final pixel.
In step 519, the adjustment of the red component amplifier 103 is terminated.
In step 520, the maximum luminance difference acquisition color adjustment unit 117 calculates j / i + j and compares j / i + j with 0.001. If j / i + j is equal to or greater than 0.001, the process proceeds to step 521.

  In step 521, the maximum luminance difference acquisition color adjustment unit 117 determines that the captured image 200 includes only red, yellow, and magenta pixels when j / i + j is smaller than 0.001. That is, the photographed image 200 may be a red, yellow, or magenta pixel, or a combination of two colors including a red and yellow pixel, a yellow and magenta pixel, and a magenta and red pixel.

  When the photographed image 200 is a red and yellow pixel, a yellow and magenta pixel, and a magenta and red pixel, one color may be the ground 201, and the other color may be a character 202 and a figure 203. There is a possibility of obtaining the maximum luminance difference. For this reason, the process proceeds to step 530, and the process of obtaining the maximum luminance difference is performed in FIGS. Note that when the captured image 200 is a single pixel of red, yellow, and magenta, the maximum brightness difference cannot be acquired. In this case, processing for not acquiring the maximum brightness difference is performed in step 602 in FIG. Do.

In step 522, the maximum luminance difference acquisition color adjustment unit 117 compares j / i + j with 0.999. If j / i + j is greater than 0.999, go to step 529.
In step 523, the maximum luminance difference acquisition color adjustment unit 117 determines that the maximum luminance difference can be acquired when j / i + j is equal to or smaller than 0.999.
In step 524, j / i + j is compared with 0.5. It is determined whether any one pixel of red, yellow, or magenta is a pixel of the ground 201 or a pixel of the character 202 or the graphic 203. When j / i + j is larger than 0.5, the process proceeds to step 527, and the process of FIGS.

In step 525, when the maximum luminance difference acquisition color adjustment unit 117, j / i + j is equal to or smaller than 0.5, any one pixel of red, yellow, or magenta is determined as the pixel of the background ground 201.
In step 526, the maximum luminance difference acquisition color adjustment unit 117 determines that the character / graphic recognition unit 118 can recognize the character 202 and the graphic 203. That is, (1), (2), (8), (9), (15), (23), (24), (26), and (27) in FIG. The brightness difference in the brightness difference storage unit 115 is sent to the character / graphic recognition unit 118 to cause the character / graphic recognition unit 118 to perform recognition, and the character 202 written in black on a white background as in the past, Similar to the recognition of the figure 203, the recognition can be performed without reducing the recognition rate. The process ends.

In step 527, in this case, the maximum luminance difference acquisition color adjustment unit 117 inverts the luminance difference data stored in the luminance difference storage unit 115 with respect to the luminance difference inversion unit 120.
In step 528, the maximum luminance difference acquisition color adjusting unit 117 determines that one of red, yellow, and magenta pixels is the pixel of the character 202 and the graphic 203 with respect to the inverted luminance difference of the luminance difference storage unit 115. Then, it is determined that the character / graphic recognition unit 118 can recognize the character 202 and the graphic 203. Proceed to step 526. That is, (4), (5), (11), (16), (19), and (20) in FIG. The brightness difference in the brightness difference storage unit 115 is sent to the character / graphic recognition unit 118 to cause the character / graphic recognition unit 118 to perform recognition, and the character 202 written in black on a white background as in the past, Similar to the recognition of the figure 203, the recognition can be performed without reducing the recognition rate.

In step 529, in this case, the maximum luminance difference acquisition color adjustment unit 117 determines that the captured image 200 is composed of pixels other than red, yellow, and magenta, and leaves the processing to FIGS.
In step 530, the maximum luminance difference acquisition color adjustment unit 117 determines that there is a possibility of acquiring the maximum luminance difference.

In step 531, the maximum luminance difference acquisition color adjustment unit 117 proceeds to FIG. 20 and performs the next color adjustment process.
FIGS. 20 and 21 are flowcharts for explaining an operation example in which intermediate colors are added by the maximum luminance difference acquisition by the green component adjustment of the maximum luminance difference acquisition color adjustment unit 117 in the continuation processing of FIGS. 18 and 19.
As shown in FIG. 20, in step 541, following step 532 in FIG. 19, the maximum luminance difference acquisition color adjustment unit 117 sets the luminance difference storage unit 115 to an initial value.

In step 542, the maximum luminance difference acquisition color adjustment unit 117 initializes the capture pixel position.
In step 543, i = 0 and j = 0.
In step 345, the maximum luminance difference acquisition color adjustment unit 117 sets the maximum value of the green component amplification factor control signal 110 in the green component amplifier 104.

In step 544, the maximum luminance difference acquisition color adjustment unit 117 starts adjustment of the green component amplifier 104.
In step 546, the maximum luminance difference acquisition color adjustment unit 117 sets an initial value (a 1) in the maximum luminance storage unit 113 and an initial value (b 1) in the minimum luminance storage unit 114.
In step 547, the maximum luminance difference acquisition color adjustment unit 117 captures a one-pixel luminance signal via the pixel position information signal 119.

In step 548, the maximum luminance difference acquisition color adjustment unit 117 compares the magnitude of the detected luminance signal from the luminance signal calculation unit 116 with the initial value (a1) of the maximum luminance storage unit 113. When the magnitude of the detected luminance signal is equal to or smaller than the initial value (a1) of the maximum luminance storage unit 113, the process proceeds to step 550.
In step 549, when the magnitude of the detected luminance signal is larger than the initial value (a1) of the maximum luminance storage unit 113, the maximum luminance difference acquisition color adjustment unit 117 sets the initial value set in the maximum luminance storage unit 113. (A1) is rewritten to the magnitude (d1) of the luminance signal.

In step 550, the maximum luminance difference acquisition color adjustment unit 117 compares the magnitude of the detected luminance signal from the luminance signal calculation unit 116 with the initial value (b 1) of the minimum luminance storage unit 114. If the detected luminance signal is equal to or larger than the initial value (b1) of the minimum luminance storage unit 114, the process proceeds to step 552.
In step 551, the maximum luminance difference acquisition color adjustment unit 117 determines that the detected luminance signal is smaller than the initial value (b1) of the minimum luminance storage unit 114, and the initial value set in the minimum luminance storage unit 114. (B1) is rewritten to the magnitude (c1) of the luminance signal.

  In step 552, the maximum luminance difference acquisition color adjustment unit 117 performs an operation of the maximum luminance storage unit 113 -minimum luminance storage unit 114 on the values stored in the maximum luminance storage unit 113 and the minimum luminance storage unit 114 to obtain the luminance difference. The initial value (a1-b1) of the storage unit 115 is compared with the calculation result of the maximum luminance storage unit 113-minimum luminance storage unit 114. When the initial value (a1-b1) of the luminance difference storage unit 115 is larger than the calculation result (a1-c1) of the maximum luminance storage unit 113-minimum luminance storage unit 114, the process proceeds to step 553, and the luminance difference storage unit 115 When the initial value (a1-b1) is equal to or smaller than the calculation result (d1-b1) of the maximum luminance storage unit 113-minimum luminance storage unit 114, the process proceeds to step 554.

  In step 553, in this case, it means that the luminance of the captured pixel is small despite the maximum value setting of the green component amplification factor control signal 110. That is, j means the number of pixels having a small luminance difference, and as described above, the pixels having a small luminance difference constitute the character 202 and the graphic 203. j = j + 1 is set, the number of pixels to be the character 202 and the graphic 203 is calculated, and the process proceeds to step 556.

In step 554, the maximum luminance difference acquisition color adjustment unit 117 calculates the initial value (a1-b1) set in the luminance difference storage unit 115 as the calculation result (d1-b1) of the maximum luminance storage unit 113-minimum luminance storage unit 114. Rewrite as
In step 555, in this case, it means that the luminance of the captured pixel is increased by setting the maximum value of the green component amplification factor control signal 110. That is, i means the number of pixels having a large luminance difference, and pixels having a large luminance difference constitute the ground 201 as described above. i = i + 1 and the number of pixels to be the background 201 is calculated.

In step 556, the maximum luminance difference acquisition color adjustment unit 117 determines whether or not the captured pixel is the final pixel.
In step 557, if the captured pixel is not the final pixel, the maximum brightness difference acquisition color adjustment unit 117 adds the address of the captured pixel, returns to step 346, and continues the maximum brightness difference acquisition operation for the next pixel.

As shown in FIG. 21, in step 558, the maximum luminance difference acquisition color adjusting unit 117 cancels the maximum value setting of the green component amplification factor control signal 110 when the captured pixel is the final pixel.
In step 559, the adjustment of the green component amplifier 104 is terminated.
In step 560, the maximum luminance difference acquisition color adjusting unit 117 calculates j / i + j and compares j / i + j with 0.001. If j / i + j is equal to or greater than 0.001, the process proceeds to step 563.

  In step 561, the maximum luminance difference acquisition color adjustment unit 117 determines that the captured image 200 includes pixels of only green, yellow, and magenta. That is, the photographed image 200 may be a green, yellow, or magenta pixel, or a combination of two colors including a green and yellow pixel, a yellow and magenta pixel, and a magenta and green pixel.

When the photographed image 200 is a green and yellow pixel, a yellow and magenta pixel, and a magenta and green pixel, one color may be the ground 201 and the other color may be a character 202 and a figure 203. There is a possibility of obtaining the maximum luminance difference. For this reason, the process proceeds to step 570 and is left to the processes of FIGS.
Since the maximum brightness difference cannot be acquired when the captured image 200 is a single pixel of green, yellow, and magenta, in this case, the process of not acquiring the maximum brightness difference is performed in step 602 in FIG. Do.

In step 562, the maximum luminance difference acquisition color adjustment unit 117 compares j / i + j with 0.999. If j / i + j is greater than 0.999, go to step 569.
In step 563, the maximum luminance difference acquisition color adjustment unit 117 determines that the maximum luminance difference can be acquired when j / i + j is equal to or smaller than 0.999.
In step 564, j / i + j is compared with 0.5. It is determined whether any one of the green, yellow, and cyan pixels is the pixel of the ground 201 or the pixel of the character 202 and the graphic 203. If j / i + j is greater than 0.5, go to step 567.

In step 565, when the maximum luminance difference acquisition color adjusting unit 117, j / i + j is equal to or smaller than 0.5, any one of green, yellow, and cyan pixels is determined as the pixel of the background ground 201.
In step 566, the maximum luminance difference acquisition color adjustment unit 117 determines that the character 202 and graphic 203 can be recognized by the character / graphic recognition unit 118. That is, it corresponds to (3), (7), (12), (17), (22), (28), and (30) in FIG. The brightness difference in the brightness difference storage unit 115 is sent to the character / graphic recognition unit 118 to cause the character / graphic recognition unit 118 to perform recognition, and the character 202 written in black on a white background as in the past, Similar to the recognition of the figure 203, the recognition can be performed without reducing the recognition rate. The process ends.

In step 567, in this case, the maximum luminance difference acquisition color adjustment unit 117 inverts the luminance difference data stored in the luminance difference storage unit 115 with respect to the luminance difference inversion unit 120.
In step 568, the maximum luminance difference acquisition color adjustment unit 117 replaces the inverted luminance difference in the luminance difference storage unit 115 with any one of green, yellow, and cyan pixels as the character 202 and graphic 203 pixels. Then, it is determined that the character / graphic recognition unit 118 can recognize the character 202 and the graphic 203. Proceed to step 566. That is, (6), (10), (13), and (21) in FIG. The brightness / difference stored in the brightness difference storage unit 115 is sent to the character / graphic recognition unit 118 to cause the character / graphic recognition unit 118 to perform the recognition. As in the case of 203, recognition can be performed without reducing the recognition rate.

In step 569, in this case, the maximum luminance difference acquisition color adjustment unit 117 determines that the captured image 200 is composed of pixels other than green, yellow, or magenta, and leaves the processing to FIGS. 22 and 23.
In step 570, the maximum luminance difference acquisition color adjustment unit 117 determines that there is a possibility of acquiring the maximum luminance difference.

In step 571, the maximum luminance difference acquisition color adjustment unit 117 proceeds to FIG. 22, and performs the next color adjustment process.
FIGS. 22 and 23 are flowcharts for explaining an operation example in which the intermediate color is added by the maximum luminance difference acquisition by the blue component adjustment of the maximum luminance difference acquisition color adjustment unit 117 in the continuation processing of FIGS.
As shown in FIG. 22, in step 581, the maximum luminance difference acquisition color adjustment unit 117 sets the luminance difference storage unit 115 to an initial value following step 571 in FIG. 21.

In step 582, the maximum luminance difference acquisition color adjustment unit 117 initializes the capture pixel position.
In step 583, i = 0 and j = 0.
In step 584, the maximum luminance difference acquisition color adjustment unit 117 sets the maximum value of the blue component amplification factor control signal 111 in the blue component amplifier 105.

In step 585, the maximum luminance difference acquisition color adjustment unit 117 starts adjustment of the blue component amplifier 105.
In step 586, the maximum luminance difference acquisition color adjustment unit 117 sets an initial value (a1) in the maximum luminance storage unit 113 and sets an initial value (b1) in the minimum luminance storage unit 114.
In step 587, the maximum luminance difference acquisition color adjustment unit 117 captures a one-pixel luminance signal via the pixel position information signal 119.

In step 588, the maximum luminance difference acquisition color adjustment unit 117 compares the magnitude of the detected luminance signal from the luminance signal calculation unit 116 with the initial value (a1) of the maximum luminance storage unit 113. When the magnitude of the detected luminance signal is equal to or smaller than the initial value (a1) of the maximum luminance storage unit 113, the process proceeds to step 590.
In step 589, when the magnitude of the detected luminance signal is larger than the initial value (a1) of the maximum luminance storage unit 113, the maximum luminance difference acquisition color adjustment unit 117 sets the initial value set in the maximum luminance storage unit 113. (A1) is rewritten to the magnitude (d1) of the luminance signal.

In step 590, the maximum luminance difference acquisition color adjustment unit 117 compares the magnitude of the detected luminance signal from the luminance signal calculation unit 116 with the initial value (b1) of the minimum luminance storage unit 114. When the magnitude of the detected luminance signal is equal to or larger than the initial value (b1) of the minimum luminance storage unit 114, the process proceeds to step 592.
In step 591, if the magnitude of the detected luminance signal is smaller than the initial value (b1) of the minimum luminance storage unit 114, the maximum luminance difference acquisition color adjustment unit 117 sets the initial value set in the minimum luminance storage unit 114. (B1) is rewritten to the magnitude (c1) of the luminance signal.

  In step 592, the maximum luminance difference acquisition color adjustment unit 117 calculates the maximum luminance storage unit 113 and the minimum luminance storage unit 114 for the values stored in the maximum luminance storage unit 113 and the minimum luminance storage unit 114, thereby calculating the luminance difference. The initial value (a1-b1) of the storage unit 115 is compared with the calculation result of the maximum luminance storage unit 113-minimum luminance storage unit 114. When the initial value (a1-b1) of the luminance difference storage unit 115 is larger than the calculation result (a1-c1) of the maximum luminance storage unit 113-minimum luminance storage unit 114, the process proceeds to step 593 and the luminance difference storage unit 115 When the initial value (a1-b1) is equal to or smaller than the calculation result (d1-b1) of the maximum luminance storage unit 113-minimum luminance storage unit 114, the process proceeds to step 594.

  In step 593, this means that the captured pixel has a low luminance despite the maximum value setting of the blue component amplification factor control signal 111. That is, j means the number of pixels having a small luminance difference, and as described above, the pixels having a small luminance difference constitute the character 202 and the graphic 203. j = j + 1 is set, and the number of pixels to be the character and graphic 203 is calculated.

In step 594, the maximum luminance difference acquisition color adjustment unit 117 calculates the initial value (a1-b1) set in the luminance difference storage unit 115 as the calculation result (d1-b1) of the maximum luminance storage unit 113-minimum luminance storage unit 114. Rewrite as
In step 595, in this case, it means that the luminance of the captured pixel is increased by setting the maximum value of the blue component amplification factor control signal 111. That is, i means the number of pixels having a large luminance difference, and pixels having a large luminance difference constitute the ground 201 as described above. i = i + 1 and the number of pixels to be the background 201 is calculated.

In step 596, the maximum luminance difference acquisition color adjustment unit 117 determines whether or not the captured pixel is the final pixel.
In step 597, if the captured pixel is not the final pixel, the maximum brightness difference acquisition color adjustment unit 117 adds the address of the captured pixel, returns to step 586, and continues the maximum brightness difference acquisition operation for the next pixel.

As shown in FIG. 23, in step 598, the maximum luminance difference acquisition color adjusting unit 117 cancels the setting of the maximum value of the blue component amplification factor control signal 111 when the captured pixel is the final pixel.
In step 599, the adjustment of the blue component amplifier 105 is terminated.
In step 600, the maximum luminance difference acquisition color adjustment unit 117 calculates j / i + j and compares j / i + j with 0.001. If j / i + j is equal to or greater than 0.001, the process proceeds to step 603.

In step 601, the maximum luminance difference acquisition color adjusting unit 117 determines that the captured image 200 is composed of a single pixel of blue, cyan, or magenta when j / i + j is smaller than 0.001.
In step 602, the maximum luminance difference acquisition color adjustment unit 117 determines that the maximum luminance difference acquisition is impossible and ends the processing.

In step 603, the maximum luminance difference acquisition color adjustment unit 117 compares j / i + j with 0.999. If j / i + j is greater than 0.999, go to step 605.
In step 604, in this case, the maximum luminance difference acquisition color adjustment unit 117 determines that the captured image 200 is composed of single pixels of red, yellow, or green that should be the character 202 and the graphic 203. Proceeding to step 602, a process for not obtaining the maximum luminance difference is performed.

In step 605, in this case, the maximum luminance difference acquisition color adjustment unit 117 determines that the maximum luminance difference can be acquired.
In step 606, j / i + j is compared with 0.5. It is determined whether any one pixel of blue, cyan, or magenta is a pixel of the ground 201 or a pixel of the character 202 or the graphic 203. If j / i + j is greater than 0.5, go to step 609.
In step 607, when the maximum luminance difference acquisition color adjusting unit 117, j / i + j is equal to or smaller than 0.5, any one pixel of blue, cyan, or magenta is determined as the pixel of the background ground 201.

  In step 608, the maximum luminance difference acquisition color adjustment unit 117 determines that the character 202 and graphic 203 can be recognized by the character / graphic recognition unit 118. That is, it corresponds to (25) and (29) of FIG. The brightness difference in the brightness difference storage unit 115 is sent to the character / graphic recognition unit 118 to cause the character / graphic recognition unit 118 to perform recognition, and the character 202 written in black on a white background as in the past, Similar to the recognition of the figure 203, the recognition can be performed without reducing the recognition rate. The process ends.

In step 609, in this case, the maximum luminance difference acquisition color adjustment unit 117 inverts the luminance difference data stored in the luminance difference storage unit 115 with respect to the luminance difference inversion unit 120.
In step 610, the maximum luminance difference acquisition color adjustment unit 117 determines that one of blue, cyan, and magenta pixels is the pixel of the character 202 and the graphic 203 for the inverted luminance difference of the luminance difference storage unit 115. Then, it is determined that the character / graphic recognition unit 118 can recognize the character 202 and the graphic 203. Proceed to step 608. That is, (14) and (18) in FIG. The brightness difference in the brightness difference storage unit 115 is sent to the character / graphic recognition unit 118 to cause the character / graphic recognition unit 118 to perform recognition, and the character 202 written in black on a white background as in the past, Similar to the recognition of the figure 203, the recognition can be performed without reducing the recognition rate.

FIG. 24 is a diagram for explaining combinations of the three intermediate colors of red, green, and blue primary colors, yellow, cyan, and magenta in the ground image 201 and the character 202 and the graphic 203 in FIG.
As shown in the figure, in the combination of the colors of the background 201, the character 202, and the figure 203, any two different colors can be selected from three intermediate colors of red, green, and blue, yellow, cyan, and magenta. There are 30 types of combinations of the photographed image 200 in which the color of the ground 201, the character 202, and the color of the figure 203 are used.

  In order to obtain the maximum luminance difference for the 30 types of combinations in FIG. 24, as described above, the processing in FIGS. 18 and 19 and the processing in FIGS. 18 and 19 (inversion: see steps 527 and 528). 18, FIG. 19 → FIG. 20, FIG. 21, processing of FIG. 18, FIG. 19 → FIG. 20, FIG. 21 (inversion: refer to step 567, step 568), FIG. 18, FIG. → The processing of FIG. 22 and FIG. 23, FIG. 18, FIG. 19 → FIG. 20, FIG. 21 → FIG. 22, FIG. 23 (reversal: see step 609 and step 610) are required.

  Therefore, according to the present invention, the amplification factors of the red component, the green component, and the blue component with the amplification factors set to the minimum are sequentially maximized, and the three primary colors of red, green, and blue, yellow, cyan, and magenta. The color adjustment is performed so as to maximize the luminance difference between the colors of one of the two colors 201 that are arbitrarily combined out of the intermediate colors and minimize the luminance difference between the characters 202 and the figure 203. The character 202 and the graphic 203 can be recognized without reducing the recognition rate in the same manner as the recognition of the character 202 and the graphic 203 written in black on a white background.

FIG. 25 is a block diagram showing a schematic configuration of the color adjustment system of the color camera when the red, green, and blue component electrical signals of the pixel are time-division multiplexed in the third modification of FIG. As shown in this figure, compared with FIG. 1, an amplifier 131 and an A / D converter 132 are provided between the image sensor 102 and the signal processing unit 112.
The image sensor 102 time-division-multiplexes the converted red, green, and blue component electrical signals of the pixel and outputs the result to the amplifier 131.

The amplifier 131 has a function of amplifying the red component, green component, and blue component electrical signals of the pixels converted by the image sensor 102 and time-division multiplexed.
The A / D converter 132 has a function of converting the time-division multiplexed electric signal of the red component, the green component, and the blue component amplified by the amplifier 131 into a digital signal.
An amplification factor control signal 133 is sent from the signal processing unit 112 to the amplifier 131, and the amplification factor control signal 133 is used to control the amplification factor of the amplifier 131.

In this manner, the red, green, and blue component electrical signals of the pixels converted by the image sensor 102 with respect to the amplifier 131 and the A / D converter 132 reduced to a pair are time-division multiplexed.
Further, a red component gain control signal, a green component gain control signal, and a blue component gain control signal are time-division multiplexed on the gain control signal 133.
FIG. 26 is a diagram for explaining an operation example of the time division multiplexing of the maximum luminance difference acquisition color adjustment unit 117 of FIG.

As shown in FIG. 4A, the maximum luminance difference acquisition color adjustment unit 117 relates to pixels captured by the image sensor 102 via the pixel position information signal 119. As an example, a red component electric signal, a green component electric signal, Requests time division multiplexing in the order of the blue component electrical signal.
As shown in FIG. 5B, the maximum luminance difference acquisition color adjusting unit 117 responds to the request for time division multiplexing in the order of the red component electric signal, the green component electric signal, and the blue component electric signal, and thereby the amplification factor control signal 133, the maximum setting of the red component gain control signal (corresponding to FIG. 5), the maximum setting of the green component gain control signal (corresponding to FIG. 7), and the maximum setting of the blue component gain control signal (FIG. 9). Action).
Therefore, according to the present invention, it is possible to avoid complication of the circuit configuration.

  The present invention is applicable not only to a digital color camera but also to a portable electronic device such as a mobile phone simple telephone (PHS) or a personal digital assistant (PDA) having a color camera function.

1 is a block diagram illustrating a schematic configuration of a color camera color adjustment system according to the present invention. FIG. FIG. 3 is a diagram illustrating an example of a captured image captured by a lens 101. It is a figure explaining the value set to the red component gain control signal 109, the green component gain control signal 110, and the blue component gain control signal 111 in FIG. It is a figure explaining the magnitude | size of the detection luminance signal at the time of the initial value of the maximum luminance memory | storage part 113 in FIG. 1, and the minimum luminance memory | storage part 114, red, green, and blue component adjustment. 7 is a flowchart illustrating an example of a maximum brightness difference acquisition operation by red component adjustment of a maximum brightness difference acquisition color adjustment unit 117 in FIG. 1. 7 is a flowchart illustrating an example of a maximum brightness difference acquisition operation by red component adjustment of a maximum brightness difference acquisition color adjustment unit 117 in FIG. 1. 7 is a flowchart illustrating an example of a maximum luminance difference acquisition operation by green component adjustment of a maximum luminance difference acquisition color adjustment unit 117 in the continuation processing of FIGS. 5 and 6. 7 is a flowchart illustrating an example of a maximum luminance difference acquisition operation by green component adjustment of a maximum luminance difference acquisition color adjustment unit 117 in the continuation processing of FIGS. 5 and 6. 10 is a flowchart illustrating an example of a maximum luminance difference acquisition operation by blue component adjustment of a maximum luminance difference acquisition color adjustment unit 117 in the continuation processing of FIGS. 7 and 8. 10 is a flowchart illustrating an example of a maximum luminance difference acquisition operation by blue component adjustment of a maximum luminance difference acquisition color adjustment unit 117 in the continuation processing of FIGS. 7 and 8. It is a figure explaining the combination of the color of the background 201 of the picked-up image 200 in FIG. 2, the character 202, and the color of the figure 203. FIG. It is a block diagram which shows schematic structure of the color adjustment system of a color camera at the time of fixing the gain of one amplifier to the minimum in the 1st modification of FIG. 13 is a flowchart for explaining an operation example in which one amplification factor is fixed by acquiring a maximum luminance difference by red component adjustment of a maximum luminance difference acquisition color adjustment unit 117 in FIG. 13 is a flowchart for explaining an operation example in which one amplification factor is fixed by acquiring a maximum luminance difference by red component adjustment of a maximum luminance difference acquisition color adjustment unit 117 in FIG. 15 is a flowchart for explaining an operation example in which one amplification factor is fixed by acquiring the maximum luminance difference by blue component adjustment of the maximum luminance difference acquisition color adjustment unit 117 in the continuation processing of FIGS. 13 and 14. 15 is a flowchart for explaining an operation example in which one amplification factor is fixed by acquiring the maximum luminance difference by blue component adjustment of the maximum luminance difference acquisition color adjustment unit 117 in the continuation processing of FIGS. 13 and 14. A combination of the color of the ground 201 of the photographed image 200 and the character 202 and the graphic 203 based on the maximum brightness difference acquisition operation example of the maximum brightness difference acquisition color adjusting unit 117 of FIGS. 13 to 16 will be described with reference to FIG. FIG. 7 is a flowchart for explaining an operation example in which an intermediate color is added in the maximum luminance difference acquisition by red component adjustment of the maximum luminance difference acquisition color adjustment unit 117 in FIG. 1. 7 is a flowchart for explaining an operation example in which an intermediate color is added in the maximum luminance difference acquisition by red component adjustment of the maximum luminance difference acquisition color adjustment unit 117 in FIG. 1. 20 is a flowchart for explaining an operation example in which intermediate colors are added in the maximum luminance difference acquisition by green component adjustment of the maximum luminance difference acquisition color adjustment unit 117 in the continuation processing of FIGS. 18 and 19. 20 is a flowchart for explaining an operation example in which intermediate colors are added in the maximum luminance difference acquisition by green component adjustment of the maximum luminance difference acquisition color adjustment unit 117 in the continuation processing of FIGS. 18 and 19. FIG. 22 is a flowchart for explaining an operation example in which intermediate colors are added by the maximum luminance difference acquisition by blue component adjustment of the maximum luminance difference acquisition color adjustment unit 117 in the continuation processing of FIGS. 20 and 21. FIG. 22 is a flowchart for explaining an operation example in which intermediate colors are added by the maximum luminance difference acquisition by blue component adjustment of the maximum luminance difference acquisition color adjustment unit 117 in the continuation processing of FIGS. 20 and 21. FIG. 3 is a diagram for explaining a combination of three intermediate colors of red, green, and blue primary colors, yellow, cyan, and magenta of a ground image 201, a character 202, and a graphic 203 in FIG. It is a block diagram which shows schematic structure of the color adjustment system of a color camera when the electrical signal of the red component of a pixel, the green component, and the blue component is time-division multiplexed in the 3rd modification of FIG. FIG. 26 is a diagram for explaining an operation example during time-division multiplexing of the maximum luminance difference acquisition color adjustment unit 117 in FIG. 25.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Lens 102 ... Image sensor 103 ... Red component amplifier 104 ... Green component amplifier 105 ... Blue component amplifier 106 ... Red component A / D converter 107 ... Green component A / D converter 108 ... Blue component A / D converter 109 ... Red component amplification factor control signal 110 ... Green component amplification factor control signal 111 ... Blue component amplification factor control signal 112 ... Signal processing unit 113 ... Maximum luminance storage unit 114 ... Minimum luminance storage unit 115 ... Luminance difference storage unit 116 ... Luminance signal Calculation unit 117 ... Maximum luminance difference acquisition color adjustment unit 118 ... Character / graphic recognition unit 119 ... Pixel position information signal 120 ... Luminance difference inversion unit 131 ... Amplifier 132 ... A / D converter 133 ... Amplification rate control signal 200 ... Photographed image 201 ... Ground 202 ... Character 203 ... Graphic

Claims (8)

In color camera color adjustment systems that adjust the color of red, blue, and green components,
The red, green, and blue components of the photographed image formed by focusing the image of the other color on the ground of one color of red, green, and blue, and the image of the other color on the ground. An image sensor to convert,
An amplification unit that amplifies the electrical signals of the red component, green component, and blue component converted by the image sensor,
A luminance calculation unit that obtains luminance from the electrical signals of the red component, green component, and blue component amplified by the amplification unit;
A maximum luminance storage unit for storing the maximum luminance of the electrical signal of the red component, the green component, and the blue component amplified by the amplification unit as the luminance of one of the ground, the character, and the figure;
A minimum luminance storage unit for storing the minimum luminance of the electrical signals of the red component, the green component, and the blue component amplified by the amplification unit as the other luminance of the ground, the character, and the figure;
A luminance difference storage unit that stores a luminance difference between the maximum luminance stored in the maximum luminance storage unit and the minimum luminance stored in the minimum luminance storage unit as a maximum luminance difference;
The amplification factor for amplifying the red component, green component, and blue component electrical signals of the amplification unit is set to a minimum value as an initial value, one of the amplification factors is sequentially set to a maximum value, and the luminance difference storage unit is the character and the location via, e Bei the maximum luminance difference acquired color adjustment unit for performing color adjustment so as to obtain the maximum luminance difference between the figures,
The maximum luminance difference acquisition color adjustment unit sets one amplification factor to a maximum value, and determines that the image is only the ground when the luminance difference stored in the luminance difference storage unit is only the maximum luminance difference. When the operation of obtaining the maximum luminance difference is stopped and the luminance difference stored in the luminance difference storage unit is only the minimum luminance difference, one amplification factor is returned to the initial minimum value, and the other amplification factors are A color camera color adjustment system characterized in that the maximum brightness difference is obtained by setting the maximum to the maximum . The maximum luminance difference acquisition color adjusting unit determines the maximum luminance difference when the number of pixels in which the luminance difference stored in the luminance difference storage unit is the maximum luminance difference is ½ or more of the number of pixels of the photographed image. 2. The color adjustment of a color camera according to claim 1, wherein it is determined that a certain pixel forms one of a ground, a character, and a figure, and a pixel having a minimum luminance difference forms the other of the ground, the character, and the figure. system. The maximum luminance difference acquisition color adjustment unit fixes an amplification factor for amplifying any one of the red component, green component, and blue component electrical signals of the amplification unit to a minimum value that is an initial value, and sets the other two The amplification factor of the electric signal is sequentially set to the maximum value, and the number of pixels when the luminance difference stored in the luminance difference storage unit is the maximum luminance difference is compared with the number of pixels when the luminance difference is not the maximum luminance difference. Judging the number of pixels and the number of pixels of the character and the figure, when the number of pixels of the character and the figure is larger than the number of pixels of the ground, the luminance difference stored in the luminance difference storage unit is inverted, the character, The color adjustment system for a color camera according to claim 1, wherein the luminance of the figure is the luminance of the ground, and the luminance of the ground is the luminance of characters and figures. In color camera color adjustment systems that adjust the color of red, blue, and green components,
The red component, green component, and blue component of the photographed image formed by condensing the image with the characters and figures of the other color on the ground of one color of red, green, blue, yellow, cyan, and magenta. An image sensor that converts components into electrical signals;
An amplification unit that amplifies the electrical signals of the red component, green component, and blue component converted by the image sensor,
A luminance calculation unit that obtains luminance from the electrical signals of the red component, green component, and blue component amplified by the amplification unit;
A maximum luminance storage unit for storing the maximum luminance of the electrical signal of the red component, the green component, and the blue component amplified by the amplification unit as the luminance of one of the ground, the character, and the figure;
A minimum luminance storage unit for storing the minimum luminance of the electrical signals of the red component, the green component, and the blue component amplified by the amplification unit as the other luminance of the ground, the character, and the figure;
A luminance difference storage unit that stores a luminance difference between the maximum luminance stored in the maximum luminance storage unit and the minimum luminance stored in the minimum luminance storage unit as a maximum luminance difference;
The amplification factor for amplifying the red component, green component, and blue component electrical signals of the amplification unit is set to a minimum value as an initial value, one of the amplification factors is sequentially set to a maximum value, and the luminance difference storage unit is And adjusting the color so as to obtain the maximum luminance difference between the ground, the character, and the figure, the number of pixels when the luminance difference stored in the luminance difference storage unit is the maximum luminance difference, and the maximum luminance When the number of pixels in the character and the figure is larger than the number of pixels in the ground, the luminance difference storage unit is compared. And a maximum brightness difference acquisition color adjustment unit that reverses the luminance difference stored in the image, sets the luminance of characters and figures as the luminance of the ground, and sets the luminance of the ground as the luminance of the characters and graphics. Color camera color adjustment system. The maximum luminance difference acquisition color adjusting unit sets one amplification factor to a maximum value, and the luminance difference stored in the luminance difference storage unit is only the maximum luminance difference or only the minimum luminance difference. 5. The color according to claim 4 , wherein one of the amplification factors is returned to a minimum initial value, the other amplification factor is set to a maximum, and the next maximum luminance difference is obtained. Camera color adjustment system. The maximum luminance difference acquisition color adjustment unit provides information requesting time division multiplexing to the image sensor, and the image sensor converts red, green, and blue component electrical signals converted based on the provided information. Time division multiplexing, the maximum luminance difference acquisition color adjustment unit sets amplification factors for amplifying the electric signals of the red component, the green component, and the blue component that are time division multiplexed to the amplifier, and the amplification unit sets the maximum luminance division multiplexed red component when by the image sensor at an amplification rate set by the difference obtaining color adjustment unit, the green component, characterized in that amplifying the electrical signal of the blue component, to claim 1 or claim 4 Color camera color adjustment system as described. In the color camera color adjustment method that adjusts the color of red, blue, and green components,
The red, green, and blue components of the photographed image formed by focusing the image of the other color on the ground of one color of red, green, and blue, and the image of the other color on the ground. Converting, and
Amplifying the converted electrical signals of red, green and blue components respectively;
Obtaining luminance from the amplified red, green, and blue electrical signals;
Storing the maximum luminance of the amplified red, green, and blue electrical signals as the luminance of one of the ground, the character, and the figure;
Storing the minimum luminance of the amplified red component, green component, and blue component electrical signals as the other luminance of the ground, the character, and the figure;
Storing the difference between the stored maximum brightness and the stored minimum brightness as the maximum brightness difference;
The amplification factor for amplifying the electrical signals of the red component, green component, and blue component is set to the minimum value as an initial value, and one of the amplification factors is sequentially set to the maximum value, and the space between the ground, the character, and the figure is set. Adjusting the color so as to obtain the maximum luminance difference;
When one of the amplification factors is set to the maximum value and the stored luminance difference is only the maximum luminance difference, it is determined that the image is only the ground, and the operation of obtaining the maximum luminance difference is stopped, and the stored luminance When the difference is only the minimum luminance difference, the method includes the step of returning one amplification factor to the initial minimum value and setting the other amplification factor to the maximum value to obtain the next maximum luminance difference. Color camera color adjustment method. The character / graphic recognition method using the color adjustment system of a color camera according to claim 1, wherein the luminance difference stored in the luminance difference storage unit is inputted to recognize characters and graphics.

Images