JPH0695763B2 - Color image processor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a color image display device, particularly to a contour image signal of the color image signals to clarify
It is intended to obtain an image.

[0002]

2. Description of the Related Art Image display devices such as televisions and copying machines have come into widespread use and are used for general households and offices. The image of these image display devices is required to be visually preferable from the side of the user, rather than the naturalness as it is. For example, in a color television image, the flesh color is made whiter than the natural color, and the flesh color is displayed in accordance with the memory color that humans perceive as preferable. As described above, as another example of conversion processing into an image that is visually preferable or visually matched, there is a method in which the contour is emphasized and displayed. This is based on the fact that human beings mainly recognize things based on outline information, and in a display object intended to make a particularly strong impression, especially in a poster or the like, character outlines are performed to make the outline of the character stand out. In some cases.

Next, a conventional example for obtaining an image in which the contour is emphasized in the image display device will be described. The contour-enhanced image is formed by adding the original image and the contour image, and the contour image is regarded as an image composed of high-frequency signal components of the original image. As a method of extracting the high frequency signal of the original image, for example, an image whose absolute value of a difference signal between the original image and the image whose position is slightly deviated from the original image is formed as a signal. . An image signal composed of the absolute value of the signal obtained by spatially differentiating the signal of the original image is obtained, and the high frequency component of the signal of the original image can be extracted.

As described above, optical processing, processing by an electric circuit, or processing by an electronic computer has been performed in order to obtain an image in which the contour is emphasized by adding the contour image and the original image.

[0005]

However, in the above-mentioned prior art, an image in which the contour is emphasized is obtained by enhancing the contrast of the brightness or density of the contour portion in the image, and for that purpose, it is sufficient. There is a drawback that a device capable of expressing various gradations is required.

An object of the present invention is to enhance the contour portion such as a black character by reducing the chromatic color component of the contour portion in the color processing of the image signal other than the contour portion of the image. It is an object of the present invention to provide a color image processing device that can obtain an image that is easy to see.

[0007]

In order to achieve the above object, the color image processing apparatus of the present invention comprises an input means for serially inputting a color image signal representing a target image (a line for inputting S shown in FIG. 1). , A circuit for inputting a signal obtained by raster scanning, for example, a color scanner for outputting a time series signal of a plurality of colors shown in the embodiments described later), and a line delay means (see FIG. 4). (Corresponding to the delay line 31 shown in FIG. 1), and 2 in the target image are synchronized with the input of the image signal by the input unit based on the color image signal serially input by the input unit.
Extraction means (corresponding to the configuration of 31 to 35 and 11 to 15 shown in FIG. 4) for extracting the contour image signal indicating the contour portion in the dimensional direction and the contour image signal extracted by the extraction means in synchronization with each other. A conversion unit (corresponding to the color signal conversion circuit shown in FIG. 8) for converting the chromatic color component of the color image signal input by the input unit with respect to the contour portion, and the chromatic color component by the conversion unit. Outputting means for outputting a color image signal in which the value of is reduced (corresponding to the lines after the output terminals 130 to 133 in FIG. 8).
And having.

[0008]

Embodiments of 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 portion, processing is performed so that the contour portion is conspicuous by utilizing the simultaneous contrast phenomenon of colors.

The simultaneous color contrast phenomenon will be described here for reference. Simultaneous color contrast is a phenomenon in which one color looks different depending on the other colors that are juxtaposed, and this phenomenon is further classified into contrast of lightness, contrast of hue and contrast of saturation in chromatic colors. However, this will be described individually.

(1) Contrast of luminosity in chromatic colors When a pure color is placed on a white background, a color with a lower luminosity is more clearly seen, and on the contrary, a yellow with the highest luminosity is clearly seen on a black background and a medium luminosity On gray, it is a phenomenon in which any color can exhibit its own unique characteristics.

(2) Contrast of hue For example, in a screen where red and purple are in contact with each other, the side where red is in contact with purple has an orange tint, and the side where purple is in contact with red is inclined to blue-purple. It is a phenomenon that you feel. If you put a white line or a black line on the boundary of two colors, this phenomenon disappears.

(3) Contrast of Saturation For example, comparing the case where orange with high lightness is placed on pure orange and the case where orange with the same lightness is placed on gray, When compared with the case where the red turbid color is placed on the pure red color and when the same red turbid color is placed on the gray, the saturation is higher. It is a phenomenon in which it is more saturated when placed on.

The phenomenon described above is applied in the processing field of emphasizing the apparent contrast by so-called pseudo color display in which a black and white image is displayed in different colors according to the density.

In the present embodiment, in reducing the color component of the contour portion of the color image, in consideration of the above-mentioned point, the color component of the contour portion is removed based on the phenomenon of simultaneous contrast of colors, and the medium brightness gray is obtained. Convert with to weaken the hue contrast phenomenon,
Each color in the image can exhibit its own special color to make it look more saturated, and change the lightness of gray to make the above effect more appropriate. By appropriately selecting, it is possible to weaken the brightness and saturation in a part of the image, and
It can also be applied to the display of images with features extracted during pattern recognition. FIG. 1 shows the outline of a color image display device according to the present invention, in which S is an original image signal, 1 is a contour image signal extracted from the original image signal S, and only a signal having a predetermined amplitude value or more is extracted from the contour image signal. A contour extraction processing circuit 2 for extracting, a color signal conversion processing circuit 2 for converting the output signal from the circuit 1 into a contour emphasizing color signal, and 3 a circuit 2 from the original image signal S.
Is an image conversion processing circuit for removing a portion corresponding to the output color signal and converting the removed portion by the output color signal of the circuit 2. As for the original image signal S, the present embodiment is intended to form a clear image by converting the outline portion in the color image into a color that visually emphasizes the outline, for example, gray. , Here, when the signal of the color scanner that reads color information from an image and converts it into an electric signal is an original image signal, the image signal is a time-series signal separated into yellow, magenta, cyan, and black and a luminance distribution. It is composed of a luminance signal having only information.

As can be seen from the fact that a figure can be generally recognized only with a luminance signal, the luminance signal contains contour image information. Then, the contour extraction processing circuit 1 performs processing for extracting the signal of the contour image from the above-mentioned luminance signal.
The contour image signal is extracted from the signal of the luminance signal where the amplitude value changes greatly with time, that is, the signal of the high frequency component. This processing is performed by a high-pass filter, or the original signal and this signal are processed in time. Can be performed by taking the difference signal with respect to the signal slightly delayed. The absolute value of the amplitude value of the output signal obtained by this processing represents the change amount of the luminance signal, that is, the clarity of the contour, and the time represents the position of the contour.

In this embodiment, a contour color in a color image is converted into a special color such as gray which visually emphasizes the contour, but if the conversion width is thick, a part of the image is cut off. Image quality is degraded. Therefore, it is necessary to make the conversion width appropriately thin. Therefore, the contour extraction processing circuit 1 extracts only signals whose absolute amplitude value is 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 portion to be converted into a contour emphasizing signal based on a signal having a predetermined amplitude value or more from the contour extraction processing circuit 1 and also based on the original image signal. The color signals of yellow, magenta, cyan and black which are in proportion to the contour enhancement signal and which form a predetermined color signal are formed.

The image conversion processing circuit 3 converts the color-separated signals of yellow, magenta, cyan, and black of the original image into signals for edge enhancement based on the output signals of the color signal conversion processing circuit 2. The signal at the location is deleted, and the contour enhancement signals of the colors corresponding to the deleted locations are inserted.
The output signal from the circuit 3 obtained as described above can be used for printing, for example, as each color signal component.

Next, specific examples 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 the luminance signal S ₁ obtained by raster scanning the original image signal S is input to the input terminal 10. This brightness signal S
₁ is input to the differential amplifier 12 via the delay line 11 having a delay time of about the Nyquist interval of the luminance signal S ₁ and directly to take out the difference signal between the two signals. This difference signal has information on the position of the contour image and the amount of change, and has a positive amplitude value at a place where the brightness changes from a low place to a high place, and has a negative amplitude value in the opposite case. Further, the output of the differential amplifier 12 is supplied to the full-wave rectifier circuit 13 to invert the signal component having a negative amplitude value and convert it into a signal having a positive amplitude value. The limiter 14 and the differential amplifier 15 limit the amplitude value in the output signal from the rectifier circuit 13.
Only the signal component of a predetermined slice level 14 or higher is taken out, and the output of the amplifier 15 is taken out from the output terminal 16 as the contour image signal S ₂ . 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 source capable of changing the output voltage. The variable power source 22 determines the slice level, but the slice level is made variable. By
An appropriate signal component can be extracted from the signal of the contour image.

FIG. 4 shows an embodiment of the contour extraction processing circuit 1 for extracting the contour image signals in the two-dimensional directions of the vertical and horizontal directions. Here, the luminance signal S of the original image signal S supplied to the input terminal 30 is shown. ₁ is obtained by raster scanning a two-dimensional image. The delay line 11, the differential amplifier 12, and the full-wave rectifier circuit 13 operate in the same manner as in FIG. 2 and take out the contour image signal on the same scanning line. On the other hand, the luminance signal S ₁ is directly supplied to the differential amplifier 32 via the delay line 31 having a delay time of one scanning line. That is, each luminance signal on two adjacent scanning lines is input to the amplifier 32, and the signal of the contour image in the direction orthogonal to the scanning direction is taken out. Full-wave rectifier circuit that operates in the same manner as the above-mentioned full-wave rectifier circuit 13
It is supplied to the analog switch 34 and the amplitude comparator 35 via 33. The limiter 14 and the differential amplifier 15 operate in the same manner as in FIG. 2 to obtain a signal having an amplitude component of a predetermined amplitude value or more. Amplitude comparator 35 and analog switch 34
Is also supplied with the output of the full-wave rectification circuit 13, and the signal with the larger instantaneous value is output from the above two contour image signals.
The contour image signal S _{2 in the} two-dimensional direction is extracted from 36.

FIG. 5 shows a specific example of the color signal conversion processing circuit 2 in the present invention, in which the contour image signal S ₂ from the contour extraction processing circuit 1 is supplied to the input terminal 40. Amplifier 4
1, 42, 43, and 44 form the color signal components of yellow, magenta, cyan, and black for converting the contour part, and further change the amplification factors of the amplifiers 41, 42, 43, and 44 to make the contour part You can change the type of color to insert into. The output terminals 45, 46, 47 and 48 output yellow, magenta, cyan and black signals S _Y , S _M , S _C and S _B , respectively. The amplifier 49 and the limiter 50 are for shaping the contour image signal S ₂ into a rectangular wave signal to facilitate the identification of the portion to be converted with the color signal as described above, and output such a rectangular wave signal. Take out from the terminal 51. This signal is used as an identification signal S ₃ when the original image signal and the color signal to be inserted in the contour portion are superimposed on each other in the image conversion processing circuit 3 described later.

FIG. 6 shows an embodiment of the image conversion processing circuit 3 in the present invention, in which input terminals 60, 61, 62 and 63 are provided.
Input the respective color signals Y, M, C and B of yellow, magenta, cyan and black obtained by color-separating the original image signal to
The yellow, magenta, cyan, and black color signals S _Y , S _M , S _C, and S _B to be inserted in the contour portion are input to the input terminals 64, 65, 66, and 67. Further, the identification signal S ₃ of the contour portion of the contour image output from the output terminal 51 of FIG. 5 is input to the input terminal 68. Color signals Y and S _Y , M and S _M , C and S _C and B and S _B
Respectively, Y signal processing circuit 69, M signal processing circuit 70, C
The signal is supplied to the signal processing circuit 71 and the B signal processing circuit 72. These color signal processing circuits 69 to 72 are constructed as shown in FIG. 7 for the respective color signals, construct the respective color signals constituting the image in which the contour is emphasized with respect to the original image signal, and output terminals 73, 7
Take output from 4,75 and 76, respectively, for printing.

FIG. 7 shows a concrete 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 converted into the analog switch 80 by the rectangular wave signal S ₃ indicating the position where the contour emphasis signal input to the input terminal 68 is inserted.
Is controlled so that the signal component at the position where the contour emphasis signal is inserted is deleted and input to the adder 81. Further, the edge-enhanced yellow signal S _Y input from the input terminal 64 is also supplied to the adder 81. An adder 81 adds the edge-enhanced signal S _Y and a signal obtained by deleting the signal of the conversion point of the edge portion from the original image signal Y to form a color signal of the yellow component of the edge-enhanced image. The contour-emphasized yellow color signal is taken out from the output terminal 73 and supplied to the printer. Similar processing is performed in each of the M, C, and B color signal circuits 70 to 72, and contour-emphasized color signals are obtained from the output terminals 74 to 76.

Further, in the present embodiment, FIG. 8 shows an example of the configuration of the color signal conversion processing circuit in the case of forming the color signal for converting the contour portion in association with the characteristic of the original image signal sandwiching the contour portion. In FIG. 8, the contour image signal S ₂ from the contour extraction processing circuit 1 is input to the input terminal 100. This signal is converted into a pulse waveform signal by the amplifier 101 and the limiter 102. This pulse signal represents the position of the contour to be converted. The output of the limiter 102 is supplied to the 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 the differentiating circuit 103 is supplied to the half-wave rectifiers 104 and 105. Half-wave rectifier 104 and pulse generator 106 and half-wave rectifier 105 and pulse generator
Each 107 forms a pulse signal that represents the position of the beginning and end of each contour. These pulse signals are supplied to the sample hold circuits 114 to 121 as sampling pulse signals. Further, the yellow, magenta, cyan, and black color signals Y, M, C, and B of the original image are input terminals 110, 11 respectively.
Sample and hold circuits 114,11 via 1,112 and 113
Supply to 5,116,117,118,119 and 120,121 respectively. Thereby, the sample hold circuits 114, 116, 118
And 120 hold the respective color signals at the beginning of the contour portion, and the sample hold circuits 115, 117, 119 and 121 hold the respective color signals at the end of the contour portion. The output of the pulse generator 107 and the outputs of the sample and hold circuits 114 to 121 are supplied to the color calculation circuit 122. This color calculator 12
2 can be composed of a microcomputer and a storage device, and based on the characteristics between the color signals at the beginning and end of each contour, the color signals for transforming the contour can be obtained so that yellow, magenta, cyan, and black are obtained. Amplifier 123 for each signal
Controls an amplification factor of ~ 126. In this case, it will be apparent that when the color component of the contour portion is reduced, for example, when it is changed to gray as described above, the amplification factors of the amplifiers 123 to 125 are reduced. It should be noted that the color calculation circuit 122 stores in advance, based on the measurement result, a color signal having an edge enhancement effect by the above-described contrast phenomenon of lightness, saturation, and hue to be given to the color signal sandwiching the edge. I will keep it. As described above, the output terminals 130 to 133 of the amplifiers 123 to 126 are
To output color signals S _Y , S _M , S _C and S _B for converting the contour portion.

In the above description, the color image display device according to the present embodiment has been described by taking the case of a printer that displays a color image on a paper surface or the like as an example. However, the present embodiment is applied to a color image device such as a color television or a color liquid crystal. Can also be preferably used. In the case of these display devices, RGB signals are used instead of YMC signals as separated color signals. In the above-mentioned embodiment of the present invention, the case of the signal processing for electrically extracting the contour image has been described, but the signal of the contour image is converted into the electric signal by using the scanner from the contour image which is optically taken out. It is also possible to perform signal processing as in the above-described embodiment. Alternatively, an electronic calculator can be used to form the contour image in software.

Further, although the present invention has been described above with respect to the case where the contour portion is converted with a color that visually enhances, the present invention has been described as being colorless even when the background (for example, the paper surface) for displaying the image is white or black. A visual edge enhancement effect is obtained.

As is clear from the above description, according to the present invention, the following effects can be exhibited.

(1) In the present invention, in order to emphasize the contour portion in the image, the contour portion is converted with a special color in consideration of the visual effect, so that it is applicable even when the gradation of the image display device is low. it can.

(2) Since the width or location of conversion with a special color is controlled according to the image signal, the contour suitable for the image can be emphasized.

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

(4) It is possible to emphasize a specific pixel in the image.

[0035]

As described above, according to the present invention, since the line delay means for delaying the serially input color image signal is provided, the horizontal contour in the color image input at high speed, It is possible to accurately identify and extract the contour portion of any of the contours in the vertical direction. Further, in the present invention, the chromatic color of the contour portion in the color image is reduced in synchronization with the extracted contour image signal. Therefore, for example, it is possible to reduce the chromatic color of the outline portion of a black character, obtain an image that is easy to see, and perform this process with high accuracy. That is, there is an effect that the chromatic color of the contour portion can be reduced at high speed and accurately by synchronizing the two operations.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a color image display device of the present invention.

FIG. 2 is a block diagram showing an embodiment of a contour extraction processing circuit.

FIG. 3 is a circuit diagram showing an embodiment of the limiter in FIG.

FIG. 4 is a block diagram showing another embodiment of a contour extraction processing circuit.

5 is a block diagram showing an embodiment of a color signal conversion processing circuit in FIG.

FIG. 6 is a block diagram showing an embodiment of an image conversion processing circuit in FIG.

FIG. 7 is a block diagram showing an embodiment of the color signal processing circuit.

FIG. 8 is a block diagram showing another embodiment of the color signal conversion processing circuit.

[Explanation of symbols]

S Original image signal S ₁ Luminance signal S ₂ Contour image signal S ₃ 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 rectification circuit 14 Limiter 15 Differential amplifier 16 Output terminal 20 Resistance 21 Diode 22 Variable power supply 30 Input terminal 31 Delay line 32 Differential amplifier 33 Full-wave rectifier circuit 34 Analog switch 35 Amplitude comparator 36 Output terminal 40 Input terminal 41, 42, 43, 44 Amplifier 45 , 46,47,48 Output terminal 49 Amplifier 50 Limiter 51 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 73,74,75,76 output terminal 80 analog switch 81 adder 100 input terminal 101 amplifier 102 limiter 103 differentiating circuit 104,105 half-wave rectifier circuit 106,107 pulse generator 110,111,112,113 input terminal 114,115,116,117,118,119,120,121 sample hold circuit 122 color calculation circuit 123,124 , 125,126 Amplifier 130,131,132,133 Output terminal

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI Technical indication location H04N 1/46 9068-5C (72) Inventor Hisashi Nakatsui 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Incorporated (72) Inventor Shunichi Ishihara 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Yasushi Sato 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. ( 56) References JP-A-52-103923 (JP, A)

Claims (1)

[Claims] 1. An input device for serially inputting a color image signal representing a target image, and a line delaying device, wherein the input device inputs an image signal based on the color image signal serially input by the input device. Extraction means for extracting a contour image signal indicating a two-dimensional contour portion in the target image in synchronism with the contour image signal, and inputting the contour portion by the input means in synchronism with the contour image signal extracted by the extraction means. A color image signal having a chromatic color component reduced so as to reduce the chromatic color component, and a color image signal having a chromatic color component value reduced by the conversion unit. Image processing device.