JPH10126708A - Respective enhancing circuit for image signal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a perspective enhancing circuit for an image signal which performs contour enhancement of an image without spoiling perspective sensation. SOLUTION: This circuit is provided with a means 2 which detects the foreground region and background region of an image with the size of a first order differentiation signal waveform DY1 or a second order differentiation signal waveform DY2 of the outline part area of an image on a signal level, and performs edge addition outline enhancement, transient improvement contour enhancement, or hybrid improvement contour enhancement which adaptively switches both of them in accordance with far and near regions with a characteristic that is slightly stronger than conventional technology for a foreground area and with a characteristic that is slightly weaker than the conventional technology for a background region. This can realize perspective outline enhancement that maintains naturalness and acquires a conspicuous effect in making an image in high image quality.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contour emphasis circuit for an image signal, and more particularly to a perspective emphasis circuit for an image signal suitable for emphasizing an image depth and a three-dimensional effect.

[0002]

2. Description of the Related Art In a television receiver, various signal processings for improving image quality are performed in order to improve the image quality of a television image. A typical example of this is signal processing of edge enhancement for improving the sharpness of an image.

This signal processing can be broadly divided into two methods: edge addition edge enhancement and transient improvement edge enhancement. In the former, the edge addition signal is added to the contour to improve the sharpness, and in the latter, the transient characteristics of the rising and falling edges of the signal in the contour are sharpened to improve the sharpness. Many proposals have been made for an outline emphasis circuit for realizing these.

Although these circuits are effective in improving the sharpness of an image, they also have the disadvantage that the depth and three-dimensional effect of the image are impaired. That is, since signal processing is performed with parameters having the same characteristics in both the near-field region and the far-field region of the image, unnecessary enhancement is performed in the far-field region, and the sense of depth is significantly impaired, resulting in an unnatural image.

[0005] The above-mentioned phenomenon tends to be more conspicuous as the image quality and definition become higher. Therefore,
In receiving a high-definition image such as an HDTV or an EDTV, signal processing of contour enhancement that preserves perspective is an important issue.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to provide a perspective emphasis circuit for an image signal which enhances the outline of an image without impairing the perspective.

[0007]

The present invention employs the following technical means to achieve the above object.

[0008] To detect the far and near regions of an image, one of the image signals is used.
A means for detecting a region having a large signal level of the secondary differential signal or the secondary differential signal as a near view region of an image and a region having a small signal level as a distant region of the image is employed. FIG.
The outline of this principle is shown in FIG. The figure shows the primary differential signal of the image signal at the position of the scanning lines A and B of the object on the TV screen and 2
The waveform of the next differential signal is shown. As is clear from the figure, the signal levels of the primary and secondary differential signals of the image signal are large in the near-view area (scanning line B) of the object and low in the distant-view area (scanning line A). Therefore, by this means, it is possible to roughly detect the near view area and the far view area of the object.

[0009] In the method of edge enhancement, a large amount of edge-added signal is added in an image of a foreground area.
For images in distant view areas, the amount of added edge-added signals is set small, and the amount of added edge-added signals is adaptively controlled according to the perspective area of the image. Edge-added edge enhancement, and for images in near-view areas, the gradient of transients is increased. ,
For images in the distant view area, set the gradient of the transient to be small, and select the transient enhancement contour enhancement that adaptively controls the gradient of the transient according to the perspective area of the image.For images in the near view area, select the transient enhancement contour enhancement. Edge enhancement (abbreviated as type 1) in which edge-added edge enhancement is selected in the image, edge enhancement in which the edge-added edge enhancement is selected in the foreground area image, and transient enhancement edge enhancement (type 2 in the distant view area image) ), Means.

FIG. 13 shows an outline of the outline emphasis processing. FIG. 9A shows the case of edge addition edge enhancement, in which edge enhancement is performed more strongly in the near view area and slightly weaker in the far view area. FIG. 11B shows the case of the transient enhancement contour enhancement, in which the gradient of the transient is larger in the foreground area.
In a distant view area, it is performed slightly smaller. FIG. 9C shows the case of type 1 contour enhancement, which is performed with the characteristic of transient improvement contour enhancement in the near view area and the edge added contour enhancement property in the distant view area. Although not explicitly shown in the figure, in the case of type 2 contour emphasis, the edge addition contour emphasis characteristic is used in the near view area, and the transient improvement contour emphasis property is used in the distant view area. Then, these adaptive contour enhancement means for changing the characteristics of enhancement between the near view area and the distant view area enable the contour enhancement without impairing the perspective.

In the edge-added contour enhancement, the edge-added signal is linearly processed based on a second derivative signal of the image, and the signal level is increased in a region where the signal level is positive with respect to the second derivative signal. In this case, non-linear processing for generating a signal obtained by extending the signal level by several times in a region where the signal level is negative is adopted. In this non-linear processing, it is possible to enhance the outline with good black tightness.

As an image signal, a luminance signal or RGB signals of three primary colors are employed.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described.
This will be described with reference to the block diagram shown in FIG. This embodiment is suitable for performing edge enhancement by edge-added edge enhancement when the image signal is a luminance signal. 1 in the figure is a differentiation circuit, 2
Denotes a perspective detection unit, 3 denotes a coefficient weighting unit, 4 denotes a delay unit, and 5 denotes an addition unit.

One of the luminance signals Y is input to a differentiating circuit 1 to extract a primary differential signal DY1 and a secondary differential signal DY2. The specific configuration and operation will be described later.

The perspective detecting section 2 detects the perspective area of the image based on the above-described principle, and outputs coefficient information KM for controlling the amount of addition of the edge addition signal. This specific configuration and operation will also be described later.

The coefficient weighting section 3 performs a process of multiplying the second derivative signal by a coefficient value determined by coefficient information KM. Then, an edge addition signal EG having a characteristic that the amount of addition is large in the near-view region of the image and small in the distant-view region is generated. This specific configuration will also be described later.

The signal Y 'whose time delay has been adjusted by the delay unit 4
Adds the edge addition signal EG in the addition unit 5 and obtains a luminance signal YE obtained by performing edge enhancement on the output.

FIG. 2 shows an example of the configuration of the differentiating circuit. In the figure, 6 is a one-pixel delay unit, 7 is a coefficient addition unit, 8 is a subtraction unit, 9
Is an adder.

The input luminance signal Y and the signals S1 and S2 delayed by one pixel in the one-pixel delay unit 6 are weighted by coefficient addition units 7 with coefficient values of − ／, ２ ，, and − ／, respectively. , And their outputs are added by an adder 9, and the output is added to the second derivative signal DY.
Get 2. On the other hand, the subtraction unit 8 performs a subtraction process on the signals S1 and S2, and obtains a primary differential signal DY1 at an output thereof.

FIG. 3 shows an example of the configuration of the perspective detection unit and its operation. In FIG. 10A, reference numeral 10 denotes an absolute value quantization unit, 11 denotes a binarization unit, and 12 denotes a determination unit. The primary differential signal DY1 and the secondary differential signal DY2 are subjected to absolute value quantization of the signal by the absolute value quantization unit 10 and quantization by a predetermined quantization characteristic, and output quantized signals S3 and S5. The quantized signal S3 is subjected to a binary quantization process in which a value equal to or larger than a set value is 1 and a value smaller than the set value is 0 in the binarization unit 11, and a binary signal S4 is output. The area where the signal S4 is 1 corresponds to the contour area of the image.

In the area where the signal S4 is 1, the judging section 12 performs a judgment processing of a far / far area shown in FIG. That is, when the signal level of the signal S5 exceeds the threshold value TH, it is determined to be a foreground area, and coefficient information KM designating a coefficient K1 having a larger value than the value KS of the conventional example is output. On the other hand, when the signal level of the signal S5 is less than the threshold value TH, it is determined to be a distant view area, and the coefficient information KM for specifying a coefficient K2 having a smaller value than the value KS of the conventional example
Is output. In the conventional example, the fixed value KS is specified regardless of the signal level of the signal S5. For this reason, a phenomenon occurs in which the perspective is impaired by contour enhancement.

In the area where the signal S4 is 0, the coefficient value is 0.
Is output. As a result, the signal processing of the contour enhancement is limited to the contour part of the image, and the deterioration of the image quality due to the influence of noise or the like included in the image signal can be avoided.

FIG. 4 shows an example of the configuration of the coefficient weighting section. 13A is a ROM circuit which realizes coefficient weighting by table lookup. That is, a plurality of types of coefficient values 0,
A table corresponding to K1 and K2 is provided, and the corresponding table is selected by the coefficient information KM, and the input signal D is selected by this table.
A signal resulting from coefficient weighting of Y2 is output.

FIG. 3B shows an example of input / output characteristics of the coefficient weighting operation. In the linear processing, a characteristic indicated by a solid line (output Y =
K1 · X), the characteristic indicated by the dotted line in the distant view area (output Y = K
2 · X) to obtain an output signal. On the other hand, in the non-linear processing, in the region where the input signal X is negative, the characteristic of the gradient of the straight line is several times larger (for example, in the characteristic of Y = K1 · X in the positive region,
By obtaining an output signal with the characteristic of Y = 3K1.X in the negative region, nonlinear processing of extending the signal level by several times in the region where the signal level is negative can be easily realized. Therefore,
In the ROM circuit, a table according to the input / output characteristics shown in FIG.

As described above, according to the present embodiment, it is possible to realize a circuit for performing edge enhancement without impairing the perspective of an image.

Next, a second embodiment of the present invention will be described with reference to the block diagram shown in FIG. This embodiment is suitable for performing the signal processing of the edge enhancement in both the horizontal direction and the vertical direction. 1 is a differentiation circuit, 3 is a coefficient weighting section, 4 is a delay section, 5 is an addition section, 14 is a vertical differentiation circuit, 1
Reference numeral 5 denotes a perspective detection unit.

The vertical differentiating circuit 14 extracts the primary differential signal HDY1 and the secondary differential signal HDY2 in the vertical direction. The vertical differentiating circuit 14 replaces the one-pixel delay unit 6 of FIG. 2 with a one-line delay unit. Is realized.

The distance detecting section 15 uses the horizontal primary differential signal DY1 and secondary differential signal DY2 and the vertical primary differential signal HDY1 and secondary differential signal HDY2 to perform the above-described principle. , A near-view area and a distant-view area of the image are detected.

The coefficient weighting section 3 outputs the output coefficient information KM
Accordingly, the coefficient value K1 is weighted in the near view area and the coefficient value K2 is weighted in the distant view area to generate the horizontal edge addition signal EG and the vertical edge addition signal HEG.

The adder 5 adds these signals EG and HEG to the output signal Y 'of the delay unit 4 and outputs the horizontal and horizontal signals.
A luminance signal YE in which vertical contour enhancement has been performed is obtained.

Since each block can be realized by the same configuration as in the first embodiment, the description is omitted.

As described above, according to the present embodiment, it is possible to realize a circuit that enhances the contours in the horizontal and vertical directions without impairing the perspective of the image.

Next, a third embodiment of the present invention will be described with reference to a block diagram shown in FIG. This embodiment is suitable for performing edge enhancement by edge-added edge enhancement when the image signal is a three primary color RGB signal. In the figure, 1 is a differentiating circuit, 2 is a perspective detecting section, 3 is a coefficient weighting section, 4 is a delay section, 5
Is an adder.

One of the G signals G of the three primary color signals is input to a differentiating circuit 1, and its primary differential signal DG1 and secondary differential signal D
G2 is extracted.

The perspective detection section 2 detects the perspective area of the image based on the above-described principle, and outputs coefficient information KM for controlling the amount of addition of the edge addition signal.

The coefficient weighting section 3 multiplies the second derivative signal DG2 by a coefficient value determined by the coefficient information KM. Then, the edge addition signal EGG having the characteristic that the amount of addition is large in the near view area of the image and small in the distant view area is generated.

The signals R ', whose time delays have been adjusted by the delay unit 4,
The three primary color signals RE, G obtained by adding the edge-added signal EGG in the adder 5 and performing edge enhancement on the output of the adder 5 are represented by G ′ and B ′.
Get E, BE.

The blocks of each section have the same configuration as that of the first embodiment, and a description thereof will be omitted.

As described above, according to the present embodiment, it is possible to realize a circuit for enhancing the outline in the horizontal direction without deteriorating the perspective of an image. Also, it is clear that by performing the same configuration as that of the second embodiment, it is possible to realize horizontal and vertical contour enhancement. In this embodiment, the edge-added signal of the G signal is also used for the R signal and the B signal.
Although the case of the green method has been described, it is apparent that the method can be realized by a configuration in which the outline enhancement processing is performed independently for each of the RGB signals.

Next, a fourth embodiment of the present invention will be described with reference to the block diagram shown in FIG. This embodiment is suitable for performing contour enhancement by transient enhancement contour enhancement when the image signal is a luminance signal. In the figure, 1 is a differentiating circuit, 2 is a distance detecting section, and 16 is a transient improving section.

One of the luminance signals Y is input to a differentiating circuit 1 to extract a primary differential signal DY1 and a secondary differential signal DY2.

The perspective detecting section 2 detects the perspective area of the image based on the principle described above, and outputs coefficient information KM for controlling the gradient of the transient.

The transient improving unit 16 calculates the coefficient information K
A signal at a correction point is generated by a calculation process using a gradient coefficient determined by M, and a signal YE obtained by performing an edge enhancement for transient improvement on the output thereof is obtained.

FIG. 8 shows an outline of the operation of the transient improvement unit and an example of the configuration. In FIG. 3A, the input signal is a dotted line passing through the center points (X1, Y1) and (X2, Y2). On the other hand, a solid line passing through the center point and the correction point (X2, Y3) indicates an output signal after the transient improvement. (X2
The point of Y2) follows the gradient coefficient K, and Y3 = Y2 + (K−
1) The signal of the correction point (X2, Y3) is generated by the calculation of (Y2-Y1). In the present embodiment, the value of the gradient coefficient K is set to a larger value in the foreground area than in the conventional example and to a smaller value in the distant view area than in the conventional example by the coefficient information KM.

FIG. 4B shows an example of a configuration for performing this calculation.
6 is a one-pixel delay unit, 17 is a MAX detection unit, 18 is MIN
A detecting unit, 19 is an averaging unit, 20 is a subtracting unit, 21 is a coefficient weighting unit, 22 is an adding unit, and 23 is a limiter unit.

For the input luminance signal Y and each output of the one-pixel delay section 6, the MAX detection section 17 outputs the maximum value signals MAX, M
The IN detector 18 detects the minimum value signal MIN.

The averaging unit 19 calculates the average value of the signals MAX and MIN, and outputs a signal S6 corresponding to Y1 at the center point (X1, Y1).

The subtractor 20 performs an operation of subtracting S6 from the signal S7, and outputs a signal S8 corresponding to (Y2-Y1). Then, the coefficient weighting unit 21 performs a process of multiplying the coefficient value (K-1) according to the coefficient information KM. And
The addition unit 22 adds the correction point (X2, Y
The signal S10 corresponding to Y3 of 3) is obtained. The signal level of this signal is limited by the limiter 23 so as to fall within the range of the minimum value signal MIN and the maximum value signal MAX, and a signal YE obtained by performing contour enhancement by transient improvement on this output is obtained.

As described above, according to the present embodiment, it is possible to realize a circuit for enhancing the contour without deteriorating the perspective of the image.

Next, a fifth embodiment of the present invention will be described with reference to the block diagram shown in FIG. The present embodiment is suitable for performing contour enhancement by transient improvement contour enhancement when the image signal is an RGB signal of three primary colors. In the figure, 1 is a differentiating circuit, 2 is a distance detecting section, and 16 is a transient improving section.

One of the three primary color G signals G is input to the differentiating circuit 1 and its primary differential signal DG1 and secondary differential signal DG2
And extract

The perspective detecting section 2 detects the perspective area of the image based on the principle described above, and outputs coefficient information KM for controlling the gradient of the transient.

The transient improvement section 16 calculates the coefficient information K
A signal of a correction point is generated by a calculation process using a gradient coefficient determined by M, and three primary color signals RE, GE, and BE whose output is subjected to contour enhancement for transient improvement are obtained. Note that each block of the present embodiment may be configured in the same manner as in the above-described embodiment, and a description thereof will be omitted.

As described above, according to the present embodiment, it is possible to realize a circuit for performing edge enhancement without impairing the perspective of an image.

Next, a sixth embodiment of the present invention will be described with reference to a block diagram shown in FIG. This embodiment is suitable for performing edge enhancement by type 2 of transient enhancement edge enhancement and edge-added edge enhancement when the image signal is a luminance signal. In the figure, 1 is a differentiation circuit, 2 is a perspective detection unit, 4 is a delay unit, 5 is an addition unit, 24 is a transient improvement unit, 25 is a coefficient weighting unit, and 26 is a selection unit.

One of the input luminance signals Y is input to a differentiating circuit 1 to extract a primary differential signal DY1 and a secondary differential signal DY2.

The perspective detection section 2 detects the perspective area of the image based on the above-described principle, and controls the signal for selecting the transient improvement contour enhancement signal in the distant view area and the edge addition contour enhancement signal in the near view area. Output SL.

The transient improving section 24 generates a signal of a correction point by a calculation process using a gradient coefficient smaller than that of the conventional example corresponding to the distant view area, and outputs a luminance signal obtained by performing a transient improvement contour emphasis used in the distant view area on its output. Get YTE.

On the other hand, the coefficient weighting section 25 outputs the second derivative signal D
An operation of weighing Y2 with a coefficient value K1 corresponding to the foreground area is performed to generate an edge addition signal EG.

The addition section 5 adds the signal EG to the output signal Y 'of the delay section 4 to obtain a luminance signal YEE obtained by performing an edge-added contour emphasis used in the foreground area on the output.

The selector 26 selects and outputs one of the signals YTE and YEE according to the control signal SL. With this output, a signal YE is obtained in which a near-view area is edge-added contour enhancement and a distant-view area is subjected to transient improvement contour enhancement.

The blocks of each section of the present embodiment can be configured in the same manner as in the above-described embodiment, and a description thereof will be omitted.

As described above, according to the present embodiment, it is possible to realize a circuit that enhances an outline without deteriorating the perspective of an image.

Next, a seventh embodiment of the present invention will be described with reference to the block diagram shown in FIG. The present embodiment is suitable for performing edge enhancement by type 1 of transient improvement edge enhancement and edge-added edge enhancement when the image signal is a luminance signal. In the figure, 1 is a differentiation circuit, 2 is a perspective detection unit, 4 is a delay unit, 5 is an addition unit, 24 is a transient improvement unit, 25 is a coefficient weighting unit, and 26 is a selection unit.

One of the input luminance signals Y is input to a differentiating circuit 1 to extract a primary differential signal DY1 and a secondary differential signal DY2.

The perspective detection unit 2 detects the perspective area of the image based on the above-described principle, and controls the signal for selecting the transient enhancement contour enhancement signal in the foreground area and the edge addition contour enhancement signal in the distant view area. Output SL.

The transient improving unit 24 generates a signal of a correction point by a calculation process using a gradient coefficient larger than that of the conventional example corresponding to the foreground area, and outputs a luminance signal obtained by performing a transient improvement contour enhancement for use in the foreground area. Get YTE.

On the other hand, the coefficient weighting section 25 outputs the second derivative signal D
An operation of weighting Y2 with a coefficient value K2 corresponding to a distant view area is performed to generate an edge addition signal EG.

The addition section 5 adds the signal EG to the output signal Y 'of the delay section 4 to obtain a luminance signal YEE obtained by performing an edge-added contour emphasis used in a distant view area on the output.

Selector 26 selects and outputs one of signals YTE and YEE according to control signal SL. With this output, a signal YE is obtained in which a distant view area is edge-added contour enhancement and a near view area is subjected to transient improvement contour enhancement.

The blocks of each part of the present embodiment can be configured in the same manner as in the above-described embodiment, and the description is omitted.

As described above, according to the present embodiment, it is possible to realize a circuit that enhances an outline without deteriorating the perspective of an image.

[0073]

According to the present invention, it is possible to enhance the perspective of an image without deteriorating the natural feeling, and it is possible to obtain a remarkable effect of improving the image quality of a television image.

[Brief description of the drawings]

FIG. 1 is a block diagram of a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration example of a differentiating circuit;

FIG. 3 is a diagram illustrating a configuration example of a perspective detection unit.

FIG. 4 is a diagram illustrating a configuration example of a coefficient weighting unit;

FIG. 5 is a block diagram of a second embodiment of the present invention.

FIG. 6 is a block diagram of a third embodiment of the present invention.

FIG. 7 is a block diagram of a fourth embodiment of the present invention.

FIG. 8 is a diagram illustrating a configuration example of a transient improvement unit.

FIG. 9 is a block diagram of a fifth embodiment of the present invention.

FIG. 10 is a block diagram of a sixth embodiment of the present invention.

FIG. 11 is a block diagram of a seventh embodiment of the present invention.

FIG. 12 is a schematic diagram showing the principle of detecting a near-far area according to the present invention.

FIG. 13 is a schematic diagram of an outline emphasis process according to the present invention.

[Explanation of symbols]

1: Differentiating circuit, 2,15: Perspective detector, 3, 21, 25 ...
Coefficient weighting section, 4 delay section, 5, 9, 22 addition section, 6 1
Pixel delay unit, 7 ... coefficient addition unit, 8,20 ... subtraction unit, 10
... Absolute value quantizer, 11 ... Binarizer, 12 ... Determiner, 1
3: ROM circuit, 14: vertical differentiation circuit, 16, 24: transient improvement section, 17: MAX detection section, 18: MI
N detection unit, 19: average unit, 23: limiter unit, 26: selection unit.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Noboru Nojima 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside the multimedia system development headquarters of Hitachi, Ltd. 292 Hitachi Multimedia System Development Division, Hitachi, Ltd. (72) Inventor Kentaro Teranishi 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture, Japan Multimedia System Development Division Hitachi, Ltd. (72) Takaaki Nishiseto, Kanagawa 292, Yoshida-cho, Totsuka-ku, Yokohama-shi, Ltd.Video and Media Division, Hitachi, Ltd. (72) Inventor Satoshi Takahashi 292, Video and Media Division, Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Prefecture (72) Inventor Yasuhiro Kasahara Totsuka, Yokohama City, Kanagawa Prefecture Yoshida-cho 292 address Co., Ltd., Hitachi video information media business unit

Claims (8)

[Claims] 1. A perspective emphasis circuit for emphasizing perspective of an image signal, wherein an area having a large signal level of a first-order differential signal or a second-order differential signal of an image signal is a near-view area of an image, The small area has means for detecting the perspective of the image detected as a distant view area of the image, and means for adding an edge addition signal to the contour of the image to perform edge enhancement to enhance the edge. In the image, the addition amount of the edge addition signal is set to be large, and in the image of the distant view area, the addition amount of the edge addition signal is set to be small, and the addition amount of the edge addition signal is adaptively controlled according to the perspective area of the image. A perspective emphasis circuit for an image signal, which performs contour emphasis. 2. A perspective emphasis circuit for emphasizing the perspective of an image signal, wherein a region having a large signal level of a primary differential signal or a secondary differential signal of an image signal is a near-view region of an image, The small area has a means for detecting the perspective of the image detected as a distant view area of the image, and a means for improving the contour by sharpening the transient at the contour of the image to enhance the contour. In the image, the gradient of the transient is set to be large, and the gradient of the transient is set to be small in the image of the distant view area, and the transient improvement contour enhancement that adaptively controls the gradient of the transient according to the perspective area of the image is performed. Signal perspective emphasis circuit. 3. A perspective emphasis circuit for emphasizing the perspective of an image signal, wherein an area where a signal level of a first-order differential signal or a second-order differential signal of an image signal is large is a near-view area of an image, Means for detecting the perspective of the image to detect the small area as a distant view area of the image, Means for adding the edge addition signal to the outline of the image to enhance the outline, and Measures for the transient at the outline of the image The apparatus has a transient improvement contour enhancement means for sharpening the contour, and selects the edge-added contour enhancement for the detected near-view area image, and selects the transient improvement contour enhancement for the distant view area image. And a perspective emphasis circuit for image signals. 4. A perspective emphasis circuit for emphasizing the perspective of an image signal, wherein a region having a large signal level of a primary differential signal or a secondary differential signal of an image signal is a near-view region of an image, Means for detecting the perspective of the image to detect the small area as a distant view area of the image, Means for adding the edge addition signal to the outline of the image to enhance the outline, and Measures for the transient at the outline of the image The apparatus has a transient improvement contour enhancement means for sharpening the contour, and selects the transient improvement contour enhancement in the detected near-view area image, and selects the edge-added contour enhancement in the distant view area image. And a perspective emphasis circuit for image signals. 5. An image according to claim 1, wherein said edge-added contour enhancing means generates an edge-added signal based on a second derivative signal of the image. Signal perspective emphasis circuit. 6. The edge-added contour enhancing means extracts a second derivative signal of an image, and maintains a signal level as it is in a region where the signal level is positive with respect to the extracted second derivative signal. 5. The method according to claim 1, wherein in a region where the level is negative, non-linear processing for extending the signal level by several times is performed, and an edge-added signal is generated based on an output signal of the non-linear processing. 2. The perspective emphasis circuit for image signals according to 1. 7. A perspective enhancement circuit for an image signal, wherein the image signal according to claim 1 is a luminance signal. 8. The circuit according to claim 1, wherein said image signal is an RGB signal of three primary colors.