JPH02168788A - Color image processor - Google Patents

Abstract

PURPOSE:To emphasize a contour part and to make it easy to see an image by providing an outline extraction circuit, a generation means to generate a contour chrominance signal and a contour color addition means and making different the color processing of the contour part from the color processing of an image signal except the contour part of the image. CONSTITUTION:Only the signal of which absolute value of an amplitude value at a prescribed level or more is fetched with a contour extraction processing circuit 1. A signal to indicate a position converting into a signal for contour emphasis is formed in a chrominance signal conversion processing circuit 2 based on a signal on the prescribed amplitude value or more from the processing circuit 1. The respective chrominance signals of yellow, magenta, cyanogen and black to form the prescribed chrominance signals in proportion to the signal for contour emphasis based on the original image signal are formed. An image conversion processing circuit 3 eliminates the signal of a position to be converted with a signal for contour emphasis from the respective signals of which original image is color-separated based on the respective output signals of the processing circuits 2 and inserts the signal for contour emphasis of colors respectively corresponding to the eliminated positions.

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 a color television image, the skin color is made whiter than the natural color, and the image is displayed in accordance with the memory color that humans feel is preferable in terms of visual perception. 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 primarily recognize objects based on outline information, and in displays intended to make a particularly strong impression, such as posters, the outline of characters is often framed to make them stand out. In some cases.

Next, a conventional example for obtaining an image with enhanced contours using an image display device will be described. Images with emphasized outlines are
The contour image 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. A method for extracting the high frequency signal of this original image is, for example, from two signals of the original image and an image whose position is slightly shifted from this 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 are 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 below, the brightness or density contrast of the contour parts of the image is strengthened to obtain an image that emphasizes the contours. There was a drawback that it required equipment.

An object of the present invention is to make the color processing of the outline part different from the color processing of the image signal other than the outline part of the image.
It is an object of the present invention to provide a color image processing device that emphasizes outlines and obtains images that are easy to see.

In order to achieve such an object, the present invention provides a contour extraction circuit for extracting a contour image signal of a target image from an original image signal; generating means for generating a contour color signal;
The present invention is characterized in that it includes an imparting means for imparting an outline color to an outline portion of the target image based on an outline color signal generated by the generating means in accordance with an outline image signal extracted by the outline extracting circuit.

Embodiments 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 outline, processing is performed to make the outline more noticeable by utilizing the simultaneous color contrast phenomenon.

Here, the simultaneous color contrast phenomenon will be explained for reference. Simultaneous color contrast phenomenon refers to the phenomenon in which one color appears to have a different feel depending on other colors that are juxtaposed. These are classified separately, but we will discuss them separately.

(1) Contrast of brightness in chromatic colors When a pure color is placed on a white background, the color with low brightness can be clearly seen, while on the other hand, when placed on a black background, yellow, which has the highest brightness, can be clearly seen, and gray with medium brightness. This refers to a phenomenon in which each color can exhibit its own unique characteristics.

(2) Contrast of hues For example, in a screen where red and purple are in contact, the side where red is in contact with purple will have an orange tinge, and the side where purple or red is in contact will be more bluish-purple. A phenomenon that can be felt.

If a white or black line is placed between the two colors, this phenomenon disappears.

(3) Contrast of saturation For example, if you compare the case where a bright orange is placed on top of a pure orange, and the case where an orange with the same brightness is placed on top of a gray color, it will be placed on top of a gray color. On the other hand, if you compare the case where a deep red color is placed on top of a pure red color and the case where the same deep red color is placed on top of a gray color, the gray color will appear higher. This phenomenon refers to the phenomenon in which the color saturation appears higher when placed above the object.

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 displayed with color adjusted 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. In addition to weakening the contrast phenomenon of hues, making each color in the image exhibit its own characteristics and making it seem more saturated, and furthermore changing the brightness of gray to make the above effect more appropriate. In addition, by appropriately selecting the color for converting the outline, it is possible to weaken the brightness and saturation in a part of the image, and it can also be applied to display images from which features have been extracted during pattern recognition. do.

FIG. 1 shows an outline of 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 above a predetermined amplitude value V 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-enhanced color signal; 3 is a color signal conversion 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 the removed portion using the output color signal of the circuit 2. Regarding the original image signal S, this embodiment converts the contours in a color image into a color that visually and psychologically emphasizes the contours, for example, gray, thereby creating a clear image. Is there an original image signal from a color scanner that reads color information from an image and converts it into an electrical signal? It consists of a square signal that has only sequence signals and brightness 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 IA embedding to extract the signal of the contour image from the luminance signal described above. The contour image signal is extracted from the signal in the brightness signal where the amplitude value changes greatly over time, that is, the high frequency component signal. This can be done by taking a difference signal from a signal that is slightly delayed in time.

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 of a color image are converted to a special color, for example gray, that visually and psychologically emphasizes the contours, but if the conversion width is wide, parts of the image will be cut off and the image quality will deteriorate. decline or occur. Therefore, the conversion width needs to be appropriately narrowed. Therefore, the contour extraction processing circuit 1 does not extract only the signals whose absolute values of amplitude values are above 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 IA embedded 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 contour extraction processing circuit 1, and also converts the contour based on the original image signal. Yellow, magenta, cyan, and black color signals are formed that are proportional to the emphasis signal and form predetermined color signals.

The image conversion processing circuit 3 converts the color-separated yellow, macenta, cyan, and mother signals of the original image into signals at points to be converted into contour enhancement signals based on each output signal of the color signal conversion processing circuit 2. are deleted, and contour enhancement signals of the corresponding colors are inserted into the deleted locations. The output signal from the circuit 3 obtained above is used as each color signal component,
The example can be submitted to print.

Next, specific examples of each of the processing circuits 1, 2, and 3 shown in FIG. 1 will be described in more detail. FIG. A luminance signal S1 obtained by scanning S is input. This luminance signal S1 is input directly to the differential amplifier 12 via a delay line 11 having a delay time approximately equal to the Nyquist interval of the luminance signal S1, and a difference signal between the two signals is extracted. It has information about the position and amount of change, 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. Roughly, the output of the differential amplifier 12 is supplied to a 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 are the rectifier circuit 1
Only the signal components whose amplitude value is equal to or higher than the predetermined slice level of the limiter 14 are extracted from the output signal from the amplifier 15.
This output is taken out from the output terminal 16 as a contour image signal S2.

An example of this limiter 14 is shown in FIG.

In FIG. 3, 20 is a resistor, 21 is a diode, 22
is a variable power supply that can change the output voltage, and the aforementioned slice level is determined by this variable power supply 22. By making the slice level variable, appropriate signal components can be extracted from the signal of the contour image. It's coming.

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.
a luminance signal S of the original image signal S supplied to the input terminal 30;
is obtained by scanning a two-dimensional image. delay) J 11 , differential amplifier 12 and full-wave rectifier circuit 1
3 operates in the same manner as in the case of FIG. 2, and extracts signals of contour images on the same scanning line. On the other hand, the brightness +S is supplied directly to the differential amplifier 32 via a delay line 31 having a delay time of one scanning line. That is, this amplifier 3
In step 2, each luminance signal on two adjacent scanning lines is manually input to extract a signal of a contour image in a direction perpendicular to the scanning direction. 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 +-J in FIG. 2 to obtain a signal consisting of an amplitude component greater than a predetermined amplitude value. The amplitude comparator 35 and the analog switch 34 include a full-wave rectifier circuit 1.
3 is also supplied, and the signal with the larger instantaneous value from the following two contour image signals is taken out from the output terminal 36 as the two-dimensional contour image signal S2.

FIG. 5 shows a specific example of the color signal conversion processing circuit 2 according to the present invention, in which the outline extraction processing circuit 1 is connected to the input terminal 40.
A contour image signal S2 is supplied from.

The amplifiers 41, 42, 43 and 44 form yellow, magenta, cyan and black color signal components for converting the contour, and further change the amplification factors of the amplifiers 41, 42, 43 and 44 to convert the contour You can change the type of color inserted. Output terminal 45.4B
, 47 and 48 output yellow, magenta, cyan and black signals SY, SM, SC and Sll. 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 part to be converted by the color signal as described above. is taken out from the output terminal 51h). Note that this signal is used as an identification signal S3 when superimposing an original image signal and a color signal to be inserted into the contour 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 the input terminals 60, 61, 62, and 63 each have yellow, magenta, cyan, and black colors obtained by color-separating the original image signal. Signals Y, M, C, and B are input manually and each color signal S of yellow, macenta, cyan, and black is inserted into the contour part into input terminals 64, 65, 66, and 67.
SM, S, and Sll are manually operated. Further, the identification signal S3 of the contour portion of the contour image outputted from the output terminal 51 in FIG. 5 is input to the input terminal 68 manually.

The color signals Y and SY, M and SM, C and SC, and B and SB are supplied to a Y signal processing circuit 691, an M signal processing circuit 70, a C signal IA logic 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 13 that composes the edge-enhanced image aligned with the original image signal
The output terminals 73, 711, 75 and 76 respectively output the signals for printing.

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 inputted to the input terminal 60 controls the analog switch 80 by a rectangular waveform signal S3 inputted to the input terminal 68 and indicating the position where contour enhancement No. 13 is inserted. , the signal component at the position where the contour emphasis signal is inserted is deleted and input to the adder 81 manually. Furthermore, an adder 81 also receives an edge-enhanced yellow signal SY input from the input terminal 64.
supply to. In the adder 8j, the color signal of the yellow component of the image with the edge emphasis is formed by adding this edge-enhanced signal +SY and a signal obtained by deleting the signal of the converted part of the edge part from the original image signal Y. Then, the contour-enhanced yellow color signal is taken out from the output terminal 73 and supplied to the printer. Similar processing is performed in the M, C, and B color signal circuits 70-72, and color signals with enhanced contours are obtained from the respective output terminals 74-76.

Further, in this embodiment, an example of the configuration of the color signal conversion processing circuit in the case where a color signal for converting and shaving the contour portion is formed in relation to the characteristics of the original image signals sandwiching the contour portion is shown in FIG. 8th
In the figure, a contour image signal S2 from a contour extraction processing circuit 1 is input to an input terminal 100. This signal is transferred to the amplifier 10
1 and limiter 102 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 the differentiating circuit 103, and the rise and fall of the pulse signal (jl
Form a trigger signal indicating i, f+¥. This trigger point represents the position of the edge of each contour. Differential circuit 1
The output from 03 is fed to half wave rectifiers 104 and 105. Half-wave rectifier 104 and pulse generator 105 and wave rectifier 105 and pulse generator 107 form pulse signals representing the starting and ending positions of each contour, respectively. These pulses No. 15 are sampled and held by the circuit 11'
1 to 121 as a sunblink pulse signal. Further, each color signal Y, M, C, and B of the original image, yellow, macenta, cyan, and black, is sent to the sample-and-hold circuit 1 through human input terminals 110.1 and 1112 and 113.
14.115, 116, 117, 118, 119 and 120.121, respectively. As a result, the sample and hold circuits +14jlJ 118 and 120 hold each color signal at the start end of the contour, and the sample and hold circuits 115, 117, 119 and 121 hold each color signal at the end of the contour. Output of pulse generator 107 and sample hole 1 to circuit 114 to 1
21 are supplied to a color calculation circuit 122. This color calculation circuit 122 can be composed of a microcomputer and a storage device, and is designed to convert yellow, magenta, and other colors so that a color signal for converting the contour can be obtained based on the characteristics between each color No. 43 at the start and end of each contour. , cyan, and black signals. In this case, it will be obvious that when the color component of the contour is reduced, for example when it is changed to gray as described above, the amplification factors of the amplifiers 123 to +25 are increased by 1.-. In addition, the color calculation circuit 122 stores a color signal based on the preliminary measurement results so that a color signal having an edge enhancement 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, the amplifier 123
-126 output terminals 130-133 output color signals S, , S, , SC and SB for converting the contour.

The color image display device according to this embodiment has been described above using the case of a printer that displays color images on paper as an example, but this embodiment is also suitable for color image devices such as color televisions and color LCDs. It can be used for. In the case of these display devices, YMC (RGB signals are used instead of i) as the separated color signals. In the above-described embodiments of the present invention, the case where the signal IA is used to electrically extract the contour image is described. As mentioned above, it is also possible to use a scanner to convert the signal of the contour image into an electrical signal from the contour image extracted optically, and then perform signal processing as in the above-mentioned embodiment. It is also possible to create a contour image using software.

Furthermore, in [2] above, the present invention has been described with respect to the case where the outline is visually emphasized and converted into a dark color. , a visual contour enhancement effect can be obtained even without color.

In particular, as is clear from the above description, the following effects can be achieved according to this embodiment.

(1) In the present invention, 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 gradation of the image display device is low.

(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.

As described above, according to the present invention, it is possible to obtain an easily viewable image by emphasizing the contour portion, while reducing the color components of the contour portion.

[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 an embodiment of its contour extraction processing circuit, and FIG. 3 is a block diagram showing an embodiment of the limiter in FIG. 2. 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. 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, and FIG. 8 is a block diagram showing another embodiment of the color signal conversion processing circuit. It is. S... Original image signal, Sl... 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, 11...Delay line. 12... Differential amplifier, 13... Full wave rectifier circuit, 14... Limiter, 15... Differential amplifier. 16... Output terminal, 2D... Resistor, 21... Diode, 22..."T transformer 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, 4+, 42.43.44...Amplifier, 45.4 Oh, 4
7.48... Output terminal, 49... Amplifier, 50... Limiter, 51... Output terminal, 6 (1, 61, 62, 63J, 65.61+, 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, 75.7Ei ...Output terminal, 80...
Analog switch, 81... Adder, 100... Input terminal, +01... Amplifier, 102... Limiter, +03... Differential circuit, 101.105 10B, 107 110.111 1L4.115 ・... Half-wave rectifier circuit, ... Pulse generator, 112.113 ... Input terminal, 116.117, 118, 119.120, 121 ...
- Sample car 122...color calculation circuit, 123.124.125,126...amplifier, 130
□13+, 132, 133... Output terminals. Root circuit, Σ O ■ Procedural amendment November 27, 1999

Claims (1)

[Scope of Claims] 1) A contour extraction circuit for extracting a contour image signal of a target image from an original image signal; and an imparting means for imparting an outline color to an outline of the target image based on an outline color signal generated by the generating means in response to an outline image signal extracted by the outline extraction circuit. A color image processing device comprising: