JPH0479196B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color image display device, and particularly to a color image display device that emphasizes a contour image signal in a color image signal to obtain a clear image.

Image display 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 by emphasizing the outline. This is based on the fact that humans mainly recognize objects based on outline information, and in displays that are intended to make a particularly strong impression, such as posters, the edges of the characters are often used to make the outlines of the characters stand out. Sometimes it is done.

Next, a conventional example for obtaining an image with enhanced contours using an image display 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, an image is formed from two signals of an original image and an image whose position is slightly shifted from this image, with the absolute value of the difference signal between the two signals as a signal. 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.

However, in the conventional technology described above, the contrast of the brightness or density of the contour part in the image is increased to obtain an image in which the contour is emphasized.
There was insufficient gradation, and it was insufficient to obtain a special visual effect.

The purpose of the present invention is to
It is an object of the present invention to provide a color image processing device that emphasizes contours and obtains a special visual effect.

In order to achieve such an object, the present invention has an input means for serially inputting a color image signal representing a target image, and a line delay means, and the present invention includes an input means for serially inputting a color image signal representing a target image, and a line delay means. an extraction means for determining and extracting a contour image signal indicating a two-dimensional contour portion in the target image in synchronization with the input of the image signal by the input means, based on the contour image signal extracted by the extraction means; Synchronously, the color component of the color image signal inputted by the input means for the contour portion is a color component different from the color component, and the color component is determined by a contrast phenomenon of lightness, saturation, and hue with respect to the color image signal. The present invention is characterized by comprising a contour color converting means for converting color components into color components having an edge enhancement effect, and an output means for outputting a color image signal in which the color components of the contour portion have been converted by the contour color converting means.

The present invention will be described in detail below with reference to the drawings. In the embodiments described below, in addition to reducing the color signal of the contour, a color synchronization contrast phenomenon is used to make the contour stand out. I'm doing something like this.

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 that are 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 a white or black line is placed 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, when we compare the case where a dark red color is placed on top of a pure red color and the case where the same dark red color is placed on top of a gray color, we find that 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 apparent contrast by so-called pseudo-color display, in which a black-and-white image is colored and displayed according to 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 the present invention, where S is an original image signal, 1 is a contour image signal extracted from the original image signal S, and only signals having a predetermined amplitude value or more are 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 enhancement signal; 3 is a circuit that removes a portion corresponding to the output color signal of circuit 2 from the original image signal S; This is an image conversion processing circuit that converts a portion using the output color signal of circuit 2. In relation to the original image signal S, this embodiment aims to create a clear image 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 in the luminance signal where the amplitude value changes greatly over time, that is, the high frequency component signal. 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, the 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, and 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. The color signals of yellow, magenta, cyan, and black, which are proportional to the color signal and form predetermined color signals, are formed.

The image conversion processing circuit 3 is the color signal conversion processing circuit 2.
Based on each output signal of the original image, 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 image, and the color outline corresponding to each deleted part is Insert an emphasis signal. 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 contour extraction processing circuit 1, in which a luminance signal _S1 obtained by raster scanning an original image signal S is input to an input terminal 10. This luminance signal S ₁ is directly input to a differential amplifier 12 via a delay line 11 having a delay time approximately equal to the Nyquist interval of the luminance signal S ₁ , 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 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. 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 3
5 and the analog switch 34, the output of the full-wave rectifier circuit 13 is also supplied to the output terminal 3, and the signal with the larger instantaneous value from the above two contour image signals is sent to the output terminal 3.
6 as a two-dimensional contour image signal _S2 .

FIG. 5 shows the color signal conversion processing circuit 2 in the present invention.
A specific example will be shown 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;
By changing the amplification factors 42, 43, and 44, 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 , S _C and _SB . The amplifier 49 and the limiter 50 are for shaping the contour image signal _S2 into a rectangular wave signal to facilitate the identification of the portion to be converted by the color signal as described above, and output such a rectangular wave signal. Take it out from the terminal 51. 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 an embodiment of the image conversion processing circuit 3 according to the present invention, in which input terminals 60, 61, 6
Yellow, magenta, cyan, and black color signals Y, obtained by color-separating the original image signal into 2 and 63,
Input M, C and B, input terminals 64, 65,
Yellow, magenta, cyan, and black color signals S _Y , S _M , S _C to be inserted into the outline at 66 and 67
and enter S _B. Furthermore, the identification signal S ₃ of the contour portion of the contour image outputted from the output terminal 51 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 supplied to a Y signal processing circuit 69, an M signal processing circuit 70, a C signal processing circuit 71 and a B signal processing circuit 72, respectively. These color signal processing circuits 69 to 72 are configured for each color signal as shown in FIG.
Each color signal constituting an image whose outline has been enhanced with respect to the original image signal is constructed and taken out as output for printing from output terminals 73, 74, 75 and 76, 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 at which 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. Further, 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 at the converted portion of the edge from the original image signal Y to form 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~
Also at 72, color signals with enhanced contours subjected to similar processing are obtained from each output terminal 74-76.

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 converted into a pulse waveform signal by an amplifier 101 and a limiter 102. 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 rise and fall 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, when reducing the color components of the outline, for example, changing it to gray as described above, the amplifier 123
It would be obvious to reduce the amplification factor of ~125.
It should be noted that the color calculation circuit 122 is stored in advance based on the measurement results so that a color signal having an edge enhancement effect is given to the color signal sandwiching the outline by the above-mentioned contrast phenomenon of brightness, saturation, and hue. shall be kept. As described above, the amplifiers 123 to 12
Color signals S _Y , S _M , S _C and _SB for converting the contour portion are outputted from output terminals 130 to 133 of 6.

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.

As described in detail above, according to the present invention, the following effects can be achieved.

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

(2) Since the areas to be converted with special colors are suppressed according to the image signal, contours that match the image can be emphasized.

(3) Due to the hue contrast phenomenon, clear outlines can be formed without making the outlines stand out.

(4) It is possible to obtain an easily viewable image by emphasizing the contours in the image.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a schematic configuration of the color image display device of the present invention, FIG. 2 is a block diagram showing one embodiment of its contour extraction processing circuit, and FIG. 3 is a block diagram showing an embodiment of the limiter in 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. 7 is a block diagram showing an embodiment of the image conversion processing circuit shown in the figure. FIG. 7 is a block diagram showing an embodiment of the color signal processing circuit.
The figure is a block diagram showing another embodiment of the color signal conversion processing circuit. S...Original image signal, _S1 ...Brightness 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, 11...delay line, 12...differential amplifier,
13... Full wave rectifier circuit, 14... Limiter, 15... Differential amplifier, 16... Output terminal, 20... Resistor, 21... Diode, 22... Variable power supply, 30... Input terminal, 3
DESCRIPTION OF SYMBOLS 1... Delay line, 32... Differential amplifier, 33... Full wave rectifier circuit, 34... Analog switch, 35... Amplitude comparator, 36... Output terminal, 40... Input terminal, 41, 4
3, 43, 44...Amplifier, 45, 46, 47, 4
8...Output terminal, 49...Amplifier, 50...Limiter, 5
1...Output terminal, 60, 61, 62, 63, 64,
65, 66, 67, 68...Input terminal, 69...Y signal processing circuit, 70...M signal processing circuit, 71...C signal processing circuit, 72...B signal processing circuit, 73,7
4, 75, 76...Output terminal, 80...Analog switch, 81...Adder, 100...Input terminal, 101
...Amplifier, 102...Limiter, 103...Differential circuit,
104, 105... Half-wave rectifier circuit, 106, 107
...Pulse generator, 110, 111, 112, 11
3...Input terminal, 114, 115, 116, 11
7,118,119,120,121...sample hold circuit, 122...color calculation circuit, 123,1
24, 125, 126...Amplifier, 130, 13
1, 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 outputs 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; Regarding the part, the color component of the color image signal inputted by the input means is a color component different from the color component, and has an edge enhancement effect on the color image signal by a contrast phenomenon of brightness, saturation, and hue. A color image processing device comprising: a contour color converting means for converting the color components into color components; and an output means for outputting a color image signal in which the color components of the contour portion have been converted by the contour color converting means.