JPH0365078B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a color image processing device, and particularly to a color image processing device that emphasizes a contour image signal in a color image signal to obtain a clear image.

[Prior Art] Image processing devices such as televisions and copying machines have become widespread and are used for general home and office purposes. The images of these image display devices are required to be visually pleasing to the user rather than being naturally natural. For example, in color television images, skin tones are whiter than natural colors,
The display is made to match the memory color that humans perceive as preferable. As described above, another example of converting the image into an image that is visually preferable or consistent with the visual sense is displaying the image with its outline emphasized. This is based on the fact that humans primarily recognize objects based on contour information.
Particularly in display objects such as posters intended to make a particularly strong impression, the characters may be framed to make their outlines more noticeable.

Next, a conventional example for obtaining an image with enhanced contours using an image processing device will be described. An image with enhanced contours is formed by adding the original image and its contour image, and the contour image is considered to be an image composed of high frequency signal components of the original image. As a method for extracting the high frequency signal of this original image, for example, from two signals of the original image and an image whose position is slightly shifted from this original image, an image is formed whose signal is the absolute value of the difference signal between the two. do. In this method, an image signal consisting of the absolute value of the signal obtained by spatially differentiating the signal of the original image is obtained, and high frequency components of the signal of the original image can be extracted.

In order to obtain an image with enhanced contours by adding the contour image and the original image as described above, optical processing, processing using an electric circuit, or processing using an electronic computer has been performed.

[Problems to be Solved by the Invention] However, in the conventional techniques described above, the brightness or density contrast of the contour parts in the image is increased to obtain an image in which the contours are emphasized.
There was still room for improvement as an expression that sufficiently emphasized the outline.

An object of the present invention is to emphasize the outline by making the color processing of the outline different from the color processing of the image signal other than the outline of the image, thereby obtaining an image that is easy to see. An object of the present invention is to provide a color image processing device that can perform color image processing at high speed.

[Means for Solving the Problems] In order to achieve the above object, the color image processing device of the present invention includes input means (S shown in FIG. 1) for serially inputting a color image signal representing a target image. This corresponds to a circuit that inputs signals obtained by line and raster scanning, and corresponds to, for example, a color scanner that outputs time-series signals of multiple colors shown in the embodiments described later. (corresponding to the delay line 31 shown in the figure), and the two-dimensional direction in the target image is synchronized with the input of the image signal by the input means based on the color image signal serially input by the input means. Extraction means (31-35 and 11-3 shown in FIG.
(equivalent to the configuration of No. 15), and in synchronization with the contour image signal extracted by the extraction means, the color component of the color image signal input by the input means for the contour portion is changed to a color component different from the color component. Replacement means (output _S3 from contour extraction processing circuit 1)
(e.g., corresponds to the structure shown in FIGS. 6 and 7, in which the signal of the contour part is replaced with the contour signal S5 instead of the input signal ₅ ), and the value of the color component is replaced by the replacement means. It is characterized by having an output means for outputting a color image signal (corresponding to the terminals 73 to 76 in FIG. 6, and corresponding to, for example, an output for printing as shown in the embodiment described later).

[Examples] Examples of the present invention will be described in detail below with reference to the drawings.

In the embodiment described below, in addition to reducing the color signal of the contour part, processing is performed to make the contour part stand out by utilizing the phenomenon of simultaneous color contrast.

Here, the simultaneous color contrast phenomenon will be explained for reference. Simultaneous color contrast phenomenon refers to the phenomenon in which one color looks different depending on other colors juxtaposed, and this phenomenon is further classified into brightness contrast, hue contrast, and saturation contrast in chromatic colors. However, this will be discussed separately.

(1) Contrast of brightness in chromatic colors When a pure color is placed on a white background, the color with lower brightness will be seen more clearly.On the other hand, on a black background, yellow, which has the highest brightness, will be clearly visible, and gray, which has medium brightness, will be seen clearly. Above, it refers to a phenomenon in which any color can exhibit its own characteristics.

(2) Contrasting hues For example, on a screen where red and purple are in contact, the side where red is in contact with purple has an orange tinge, and the side where purple is in contact with red appears to be more bluish-purple. means. If you add a white or black line between the two colors, this phenomenon disappears.

(3) Contrast of saturation For example, if we compare the case where a bright orange is placed on a pure orange and the case where an orange with the same brightness is placed on a gray, On the other hand, if you compare the case where a dark red color is placed on top of a pure red color and the same case where the same dark red color is placed on a gray color, it becomes more saturated. This refers to the phenomenon in which the color saturation is perceived to be higher in the case of

The above-mentioned phenomenon is applied in the field of processing that emphasizes the contrast of people's clothing through so-called pseudo-color display, in which a black-and-white image is colored and displayed according to its density.

In this embodiment, in order to reduce the color components of the outline of a color image, in view of the above points, the color components of the outline are removed and converted into medium-light gray based on the simultaneous color contrast phenomenon. It is possible to make the above effect more appropriate by weakening the hue contrast phenomenon, bringing out the special characteristics of each color in the image, making it seem more saturated, and changing the brightness of gray. It is also possible to weaken the brightness and saturation in some parts of the image by appropriately selecting the color for converting the contours, and
It can also be applied to displaying images from which features have been extracted during pattern recognition.

FIG. 1 schematically shows a color image display device according to an embodiment of the present invention, where S is a current image signal, 1 is an original image signal, a contour image signal is extracted from the contour image signal, and a predetermined amplitude value or more is extracted from the contour image signal. 2 is a color signal conversion processing circuit that converts the output signal from circuit 1 into an edge-enhanced color signal; 3 is a portion corresponding to the output color signal of circuit 2 from the original image signal S; , and the removed portion is converted into circuit 2.
This is an image conversion processing circuit that performs conversion using the output color signal. Regarding the original image signal S, in this embodiment, a clear image is obtained by converting the contour part of a color image into a color that visually emphasizes the contour, for example, gray. , Here, if the signal of a color scanner that reads color information from an image and converts it into an electrical signal is an original image signal, that image signal is a time-series signal separated into yellow, magenta, cyan, and black, and a luminance signal. It consists of a luminance signal with only distribution information.

Note that, as can be seen from the fact that a figure can generally be recognized using only a brightness signal, the brightness signal includes information on a contour image. Then, the contour extraction processing circuit 1 performs a process of extracting a contour image signal from the luminance signal described above. The contour image signal is extracted from the signal at a point in the luminance signal where the amplitude value changes greatly over time, that is, from the signal of the high frequency component. This can be done by taking the difference signal from a slightly delayed signal.
The absolute value of the amplitude value of the output signal obtained by this processing represents the amount of change in the luminance signal, that is, the clarity of the contour, and the time represents the position of the contour.

In this embodiment, the contours in a color image are converted to a special color, such as gray, that visually emphasizes the contours psychologically, but if the conversion width is wide, part of the image will be cut off and the image quality will deteriorate. A decline occurs. Therefore, this conversion width needs to be appropriately narrowed. Therefore, the contour extraction processing circuit 1 extracts only those signals whose absolute values of amplitude values are equal to or higher than a predetermined level. The amplitude value of this signal represents the density of the color signal to be converted,
The time is used as a signal representing the position of the color signal to be converted.

The color signal conversion processing circuit 2 forms a signal representing a location to be converted into an edge enhancement signal based on the signal having a predetermined amplitude value or more from the edge extraction processing circuit 1, and performs edge enhancement based on the original image signal. Yellow, which is proportional to the color signal and forms a predetermined color signal.
Forms magenta, cyan, and black color signals.

The image conversion processing circuit 3 is the color signal conversion processing circuit 2.
Based on each output signal of the original signal, the signal of the part to be converted with the edge enhancement signal is deleted from the color-separated yellow, magenta, cyan, and black signals of the original signal, and the color corresponding to the deleted part is Insert a signal for contour enhancement. The output signal from the circuit 3 obtained in the above manner can be used for printing, for example, as each color signal component.

Next, specific examples of each of the processing circuits 1, 2, and 3 shown in FIG. 1 will be described in more detail.

FIG. 2 shows an example of the configuration of a contour extraction processing circuit that extracts contours in one-dimensional direction.
A luminance signal S ₁ obtained by raster scanning the original image signal S is input to . This luminance signal S ₁ is the luminance signal
The signal is input directly to the differential amplifier 12 via a delay line 11 having a delay time of about the Nyquist interval of _S1 , and a difference signal between the two signals is extracted. This difference signal has information on the position and amount of change in the contour image, and has a positive amplitude value where the brightness changes from a low place to a high place, and has a negative amplitude value when the brightness changes from a low place to a high place. Furthermore, the output of the differential amplifier 12 is supplied to a full-wave rectifier circuit 13 to invert the signal component with a negative amplitude value and convert it into a signal with a positive amplitude value. The limiter 14 and the differential amplifier 15 extract only the signal components whose amplitude value is equal to or higher than the predetermined slice level of the limiter 14 from the output signal from the rectifier circuit 13, and output the output of the amplifier 15 from the output terminal 16 to the contour image signal S ₂ Take it out as An example of this limiter 14 is shown in FIG.

In FIG. 3, 20 is a resistor, 21 is a diode, and 22 is a variable power supply that can change the output voltage.The above-mentioned slice level is determined by this variable power supply 22, but it is also possible to make the slice level variable. Accordingly, appropriate signal components can be extracted from the contour image signal.

FIG. 4 shows an embodiment of the contour extraction processing circuit 1 for extracting two-dimensional contour image signals in the vertical and horizontal directions. Here, the luminance signal S ₁ of the original image signal S supplied to the input terminal 30 is It was obtained by raster scanning a dimensional image. The delay line 11, the differential amplifier 12, and the full-wave rectifier circuit 13 operate in the same manner as in the case of FIG. 2, and extract signals of the contour image on the same scanning line. On the other hand, the luminance signal S ₁ is supplied directly to the differential amplifier 32 via a delay line 31 having a delay time of one scanning line. That is, each luminance signal on two adjacent scanning lines is input to this amplifier 32, and a signal of a contour image in a direction perpendicular to the scanning direction is extracted. Note that the input to the amplifier 32 is raster scanned and input to the delay line ₃ according to the input signal S1.
1, etc., the contour image signal is output as a raster scan signal synchronized with the raster scan input _S1 . The signal is supplied to an analog switch 34 and an amplitude comparator 35 via a full-wave rectifier circuit 33 that operates similarly to the full-wave rectifier circuit 13 described above. The limiter 14 and the differential amplifier 15 operate in the same manner as in FIG. 2 to obtain a signal consisting of an amplitude component greater than a predetermined amplitude value. Amplitude comparator 35 and analog switch 34
The output of the full-wave rectifier circuit 13 is also supplied to the output terminal 36, and the signal with the larger instantaneous value from the two contour image signals is taken out from the output terminal 36 as the two-dimensional contour image signal _S2 . That is, the amplitude comparator 35
Since the analog switch 34 outputs either the vertical contour signal or the horizontal contour signal, whichever is larger, it is possible to accurately output the two-dimensional contour signal.

As described above, the output of the amplifier 32 is output as a raster scan signal synchronized with the raster scan input S ₁ , so the contour image signal S is output via the full-wave rectifier circuit 33 , analog switch 34 , and differential amplifier 15 . ₂ is also a signal synchronized with raster scan input _S1 .

FIG. 5 shows a specific example of the color signal conversion processing circuit 2 in this embodiment, in which the contour image signal S ₂ from the contour extraction processing circuit 1 is supplied to the input terminal 40. Amplifiers 41, 42, 43 and 44 form yellow, magenta, cyan and black color signal components for converting contours;
When changing the amplification factors of 42, 43, and 44, for example, when converting the outline to gray as described above,
Amplifiers 41, 4 for yellow, magenta, and cyan
The amplification degree of 2,43 is lowered, and the black amplifier 44
By increasing the degree of amplification, the type of color inserted into the outline can be changed.
Output terminals 45, 46, 47 and 48 output yellow, magenta, cyan and black signals S _Y , S _M ,
Output S _C and S _B. The amplifier 49 and limiter 50 waveform-shape the contour image signal _S2 output from the differential amplifier 15 of FIG. 4 into a rectangular wave signal.
As described above, this is to facilitate identification of the location to be converted using the color signal, and such a rectangular wave signal is taken out from the output terminal 57. Note that this signal is used as an identification signal _S3 when an original image signal and a color signal to be inserted into the contour are superimposed in an image conversion processing circuit 3, which will be described later.

FIG. 6 shows the image conversion processing circuit 3 in this embodiment.
, where the input terminals 60, 61,
Yellow, magenta, cyan, and black color signals Y, M, C, and B obtained by color-separating the original image signal are input to input terminals 62 and 63, respectively.
Yellow, magenta, cyan, and black color signals S _Y to be inserted into the outline at 5, 66, and 67,
Enter S _M , S _C and S _B. Furthermore, the identification signal S ₃ of the contour portion of the contour image outputted from the output terminal 57 in FIG. 5 is input to the input terminal 68. Each color signal Y and S _Y , M and S _M , C and S _C , and B and S _B are processed by a Y signal processing circuit 69 and an M signal processing circuit 7, respectively.
0, C signal processing circuit 71 and B signal processing circuit 7
Supply to 2. These color signal processing circuits 69 to 72
are configured for each color signal as shown in FIG.
4, 75, and 76 as output for printing, respectively.

FIG. 7 shows a specific example of each color signal processing circuit shown in FIG. 6, for example, the Y signal processing circuit 69. In FIG. 7, the yellow color signal Y of the original image input to the input terminal 60 is input to the analog switch 80 by a rectangular waveform signal _S3 indicating the position where the edge enhancement signal input to the input terminal 68 is inserted. The signal component at the position where the edge enhancement signal is inserted is deleted and inputted to the adder 81. Furthermore, the edge-enhanced yellow signal S _Y input from the input terminal 64 is also input to the adder 81.
supply to. The adder 81 adds this edge-enhanced signal S _Y and a signal obtained by deleting the signal of the converted portion of the edge from the original image signal Y, thereby forming a color signal of the yellow component of the edge-enhanced image. The yellow color signal with its outline emphasized is taken out from the output terminal 73 and supplied to the printer. M, C and B color signal circuits 70~
Similar processing is performed at 72, and color signals with enhanced contours are obtained from each of the output terminals 74-76.

In other words, the contour image signal _S3 is sent to the analog switch 8.
0, the circuit of FIG. 7 constituting the replacement means synchronizes with the contour image signal _S3 and changes the color component of the color image signal input by the input means for the contour portion to be different from the color component. Can be replaced with color components.

Furthermore, in the present embodiment, FIG. 8 shows an example of the configuration of a color signal conversion processing circuit in which a color signal for converting an outline is formed in association with the characteristics of the original image signals sandwiching the outline. In FIG. 8, the input terminal 100
The contour image signal _S2 from the contour extraction processing circuit 1 is input into the circuit. This signal is sent to amplifier 101 and limiter 1.
02 to convert it into a pulse waveform signal. This pulse signal represents the position of the contour to be transformed. The output of the limiter 102 is supplied to a differentiating circuit 103 to form a trigger signal indicating the rising and falling positions of the pulse signal from the pulse signal. This trigger signal represents the position of the edge of each contour. The output from differentiating circuit 103 is supplied to half-wave rectifiers 104 and 105. Half-wave rectifier 104 and pulse generator 106 and half-wave rectifier 105 and pulse generator 107 form pulse signals representing the starting and ending positions of each contour, respectively. These pulse signals are supplied to sample and hold circuits 114 to 121 as sampling pulse signals. Furthermore, the yellow, magenta, cyan, and black color signals Y, M, C, and B of the original image are input to input terminals 110 and 1.
Sample and hold circuits 114, 115, 116, 117, 11 via 11, 112 and 113
8,119 and 120,121, respectively. Thereby, the sample and hold circuit 11
The sample and hold circuits 115, 117, 119 and 121 hold the color signals at the beginning of the contour. The output of pulse generator 107 and each output of sample and hold circuits 114 to 121 are supplied to color calculation circuit 122 . This color calculation circuit 122 can be composed of a microcomputer and a storage device, and calculates yellow, magenta, yellow, magenta, Controls the amplification factors of amplifiers 123 to 126 for cyan and black signals.

In this case, it is obvious that when reducing the color components of the contour, for example, when changing the color to gray as described above, the amplification factors of 123 to 125 are lowered. Note that the color calculation circuit 122 has memory stored in advance based on the measurement results so that a color signal having an edge-enhancing effect is given to the color signal sandwiching the edge due to the above-mentioned contrast phenomenon of brightness, saturation, and hue. shall be kept. As described above, amplifier 1
Color signals S _Y , S _M , S _C and _SB for converting the contour portion are output from output terminals 130 to 133 of 23 to 126 .

The color image display device according to this embodiment has been described above using a printer that displays color images on paper as an example, but this embodiment can also be applied to color image devices such as color televisions and color LCDs. It can be suitably used. In the case of these display devices, RGB signals are used instead of YMC signals as separated color signals. In the above-described embodiments of the present invention, the case of signal processing for electrically extracting a contour image has been described, but it is also possible to convert the signal of the contour image into an electrical signal using a scanner from the contour image extracted optically. It is also possible to perform signal processing as in the embodiments described above. Alternatively, the contour image can be formed using software using an electronic computer.

Furthermore, although the present invention has been described above with respect to the case of converting with a color that visually emphasizes the outline, when the background (for example, paper) on which the image is displayed is white or black, the outline can be visually seen even if it is colorless. A highlighting effect can be obtained.

In particular, as is clear from what has been said above,
According to this embodiment, the following effects can be achieved.

(1) In this embodiment, in order to emphasize the contours in an image, the contours are converted with a special color that takes visual effects into consideration, so it can be applied even when the image display device has low gradation.

(2) Since the width or area to be converted with a special color is controlled according to the image signal, it is possible to emphasize the outline that matches the image.

(3) It is possible to eliminate the hue contrast phenomenon.

(4) It is possible to emphasize specific pixels in an image.

[Effects of the Invention] As explained above, according to the present invention, since the present invention includes a line delay means for delaying the serially inputted color image signal, the horizontal contour in the color image inputted at high speed, It is possible to accurately identify and extract the contour of any contour in the vertical direction, and further, in the present invention, the color of the contour in a color image can be changed to another color in synchronization with the extracted contour image signal. Since this is replaced, the color conversion process of the contour part can be performed at high speed without response delay compared to the case where the gain of the amplifier is simply changed, and this process can be performed with high accuracy. That is, such 2
By synchronizing the two operations, the color conversion of the outline can be performed quickly and accurately.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a color image display device according to an embodiment of the present invention, FIG. 2 is a block diagram showing an embodiment of its contour extraction processing circuit, and FIG. A circuit diagram showing an embodiment of a limiter,
FIG. 4 is a block diagram showing another embodiment of the contour extraction processing circuit, FIG. 5 is a block diagram showing an embodiment of the color signal conversion processing circuit in FIG. 1, and FIG. 6 is an image of the image in FIG. 1. A block diagram showing an embodiment of a conversion processing circuit,
FIG. 7 is a block diagram showing an embodiment of the color signal processing circuit, and FIG. 8 is a block diagram showing another embodiment of the color signal conversion processing circuit. S...Original image signal, _S1 ...Luminance signal, _S2 ...Contour image signal, _S3 ...Identification signal, 1...Contour extraction processing circuit, 2...Color signal conversion circuit, 3...Image conversion Processing circuit, 10... Input terminal, 12... Differential amplifier, 106, 107... Pulse generator, 110,
111, 112, 113...input terminal, 114,
115, 116, 117, 118, 119, 12
0,121...sample hold circuit, 122...
...color calculation circuit, 123, 124, 125, 126
...Amplifier, 130, 131, 132, 133...
...Output terminal.

Claims (1)

[Scope of Claims] 1. An input means for serially inputting a color image signal representing a target image, and a line delay means, wherein the input means inputs a color image signal serially inputted by the input means. extraction means for determining and extracting a contour image signal indicating a contour in a two-dimensional direction in the target image in synchronization with the input of an image signal; Replacement means for replacing a color component of a color image signal inputted by the input means with a color component different from the color component; and an output for outputting a color image signal in which the value of the color component has been replaced by the replacement means. 1. A color image processing device comprising: means.