JPH057310A - System environment adaptive type contour compensating system - Google Patents

Abstract

PURPOSE:To acquire a contour compensation effect corresponding to the change of system environment so that picture quality is improved by controlling adaptively contour compensation effect quantity in a contour compensating part in accordance with various system environment parameters. CONSTITUTION:A picture signal received by a picture decoding part 1A is decoded by the picture decoding part 1A. Decoded data ia displayed on a picture display part 3 after being given the enhancement of a picture edge part by the prescribed contour compensation effect quantity by a contour compensating part 2A. At this time, the contour compensation effect quantity at the contour compensating part 2A is controlled adaptively by a contour compensation effect quantity control part 4 in accordance with the various system environment parameters. In such a configuration, the contour compensation effect corresponding to the change of the system environment is acquired, and the quality of the displayed picture can be improved drastically. Besides, it is preferable to use a transmission rate, a picture element omission rate, a moving picture/still picture, the information quantity of an input picture, and the discontinuity of the input picture as the system environment parameters in the control pare 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contour compensation method for emphasizing an edge portion of an image in order to improve image quality of a television image or the like, and more particularly to a system environment adaptive contour compensation method.

[0002]

2. Description of the Related Art In general, the quality of a processed image is better when the details are well described and the edges are clear. The former is determined by the resolution of the image processing system, and the latter is determined by the sharpness of the contour portion. In particular, the quality of the television image is greatly affected by the sharpness of the contour portion.

Although sharpness is a psychological concept, the visual Mach phenomenon is performed by performing edge compensation that gives an appropriate amount of edge-enhanced distortion (edge compensation effect amount, enhancer effect amount) to the processed and reproduced image. And emphasize the contrast phenomenon of brightness,
The sharpness of the contour portion can be obtained by visually improving the low contrast and the rising characteristic of the edge portion which are physically physical and easy to see.

FIG. 6 is a block diagram showing an image processing system to which a conventional contour compensation method is applied. In FIG. 6, 1 is an image decoding unit for decoding an image signal, and 2 is this image decoding unit. The contour compensating unit 3 for emphasizing the image edge portion according to the constant contour compensation effect amount of the decoded data obtained in 1 is based on the decoded data in which the edge portion of the image is emphasized by the contour compensating unit 2. An image display unit (for example, a TV monitor) that displays an image.

With such a configuration, the image signal input via the transmission path or the like is decoded in the image decoding unit 1, and the decoded data is converted into a constant contour compensation effect amount by the contour compensation unit 2. After the edge portion of the image is emphasized, the image is displayed on the image display unit 3.

[0006]

However, in such a conventional contour compensating method, since the edge compensating portion 2 emphasizes the image edge portion at a constant contour compensating effect amount, the image compensating effect of the image processing system is reduced. When the system environment parameters (transmission rate, pixel thinning rate, quantization table, quantization gradation, moving image / still image, display size of the image display unit 3, etc.) change, it cannot respond well, and in such a case There is a problem that the image quality deteriorates. For example, if the contour compensation effect is large when the transmission rate is low, quantization noise is emphasized and the image becomes difficult to see.

By the way, a high-efficiency coding system for moving image signals was mainly recommended by CCITT in December 1990 (H.261) for the purpose of application to video conferences or video telephones.

The recommendation stipulates the use of inter-frame / intra-frame adaptive prediction with motion compensation and DCT (discrete cosine transform). However, when the recommended transmission rate is low, the block by DCT is used. There was a problem that the distortion became noticeable.

When image coding is performed, the amount of information generated on one screen greatly depends on the design, and the amount of information in an image that is small in time and has many flat portions is small, and the amount of information that is highly moving and fine is small. The amount of information contained in a large number of images is large.

On the other hand, the line speed for transmitting the information is constant (for example, 64 kbps), and the amount of information that can be transmitted per second is limited. Therefore, the block distortion is remarkably expressed as noise when an image with a lot of movement is input.

Further, in the case of performing image coding, if the input image switching function of two channels or more or the input image resolution switching function is provided, the following problems occur.

That is, for example, when the input channel is switched, a large amount of information obviously occurs because the image contents before and after switching are not related (since the discontinuity of the input image occurs). Will end up.

The same applies to the case where there is a function for switching two or more types of resolutions. In these cases, much information is inevitably generated, and block distortion due to DCT becomes conspicuous.

The present invention has been made in view of the above problems, and provides a system environment adaptive contour compensation method which improves the image quality by obtaining the effect of contour compensation corresponding to the change of the system environment. It is intended to be provided.

[0015]

FIG. 1 (a) is a block diagram of the principle of the present invention. In FIG. 1, 1A is an image decoding unit for decoding an image signal, and 2A is an image decoding unit 1A. The contour compensating unit 3 that emphasizes the image edge portion of the decoded data according to the contour compensation effect amount is an image that displays an image based on the decoded data in which the edge portion of the image is emphasized by the contour compensating unit 2A. Display unit 4 is contour compensation unit 2
A contour compensation effect amount control unit for controlling the contour compensation effect amount in A according to the system environment parameter.

FIG. 1B is a principle block diagram showing another embodiment of the present invention. In FIG. 1B, 1B is an image coding unit, and this image coding unit 1B is a contour compensation unit 2A. The image signal from the image pickup unit 5 in which the image edge portion is emphasized according to the contour compensation effect amount is encoded by FIG.
Similar to that shown in (a), the contour compensation effect amount in the contour compensation unit 2A is controlled by the contour compensation effect amount control unit 4 according to the system environment parameter.

Here, as the system environment parameters in the contour compensation effect amount control unit 4 of the present invention shown in FIGS. 1A and 1B, the transmission rate, the pixel thinning rate, the moving image / still image, and the input image information are included. Amount, the discontinuity of the input image is used.

When the transmission rate is used, the higher the transmission rate, the greater the amount of contour compensation effect, and the edge portion of the image is emphasized. When the pixel thinning rate is used, the edge compensation effect amount is increased and the edge portion of the image is emphasized as the pixel thinning rate is lower.

When using either a moving image or a still image, the edge compensation effect amount is emphasized by increasing the edge compensation effect amount in the case of a still image, and the edge compensation effect amount in the case of a moving image. To reduce the emphasis on the edges of the image.

Further, when the information amount of the input image is used, the edge compensation amount of the image is emphasized by increasing the contour compensation effect amount as the information amount of the input image is smaller on the basis of the constant transmission rate. Furthermore, when the discontinuity of the input image is used, when the discontinuity of the input image is detected, the amount of contour compensation effect is reduced to weaken the emphasis of the edge portion of the image.

[0021]

In the invention shown in FIG. 1 (a), the image signal input to the image decoding unit 1A is the image decoding unit 1A.
The image data is decoded in (1) and the decoded data is displayed on the image display unit 3 after the edge portion of the image is emphasized by the contour compensation effect amount by the contour compensation unit 2A.

At this time, the contour compensation effect amount in the contour compensation section 2A is adaptively controlled according to various system environment parameters, and the contour compensation effect corresponding to the change of the system environment can be obtained.

Further, in the invention shown in FIG. 1B, the image signal obtained by the image pickup section 5 is emphasized at the image edge portion by the contour compensation effect amount by the contour compensation section 2A, and thereafter,
It is output to the image encoding unit 1B.

At this time, the contour compensation effect amount in the contour compensation unit 2A is adaptively controlled according to various system environment parameters, and the contour compensation effect corresponding to the change of the system environment can be obtained. Then, the image signal in which the edge portion of the image is emphasized by the contour compensation unit 2A is coded by the image coding unit 1B and output.

[0025]

Embodiments of the present invention will be described below with reference to the drawings.

(A) Description of First Embodiment FIG. 2 is a block diagram showing a first embodiment of the present invention. In FIG. 2, 1 is an image decoding / coding for decoding and coding an image signal. A converting unit 2A is a contour for emphasizing an image edge portion according to a contour compensation effect amount in the decoded data obtained by the image decoding / encoding unit 1 or the image data obtained by the TV camera (imaging unit) 5A. It is a compensation department.

Further, 3A is a TV monitor (image display unit) for displaying an image based on the decoded data in which the edge portion of the image is emphasized by the contour compensating unit 2A, and 4 is a contour compensation effect amount in the contour compensating unit 2A. In the contour compensation effect amount control unit that adaptively controls according to system environment parameters (control information from the image decoding / encoding unit 1, display size information from the TV monitor A, control information from the TV camera 5A). is there.

Here, as the system environment parameters used in the contour compensation effect amount control section 4, for example, the following (1) to (8) are used. (1) Transmission rate (2) Pixel thinning rate (subsample; For example, QCIF having a low resolution has a high thinning rate and CI having a high resolution.
F has a small thinning rate. (3) Quantization table as density when decoding / encoding in the image decoding / encoding unit 1 (density; in the case of coarse, the amount of information is small, in the case of dense) (4) Quantized gradation (A / D bit precision) (5) Video / still image (6) Display size of TV monitor 3A (7) Information amount of input image (movement of input image) (8) Discontinuity of the input image (This occurs when switching the input image of two or more channels or the function of switching the resolution of the input image when the switching is performed)

Regarding the parameters actually used as the system environment parameters, the effect amount of the contour compensation corresponding to each parameter is set in advance in several steps, for example. Specifically, the contour compensation effect amount is set for each system environment parameter according to the following tendencies (i) to (viii).

(I) In the case of the transmission rate, the higher the transmission rate, the greater the amount of contour compensation effect, and the edge portion of the image is emphasized.

(Ii) In the case of the pixel thinning rate, the lower the pixel thinning rate is, the larger the contour compensation effect amount is, and the edge portion of the image is emphasized.

(Iii) In the case of the quantization table, the denser the quantization table is, the larger the contour compensation effect amount is, and the edge portion of the image is emphasized.

(Iv) In the case of quantized gradations, the more the quantized gradations, the greater the amount of contour compensation effect, and the edge portion of the image is emphasized.

(V) When using either a moving image or a still image, if the image is a still image, the contour compensation effect amount is increased to emphasize the edge portion of the image, and if it is a moving image, the contour The amount of compensation effect is reduced and the edge portion of the image is weakened.

(Vi) In the case of the display size of the TV monitor 3A, the smaller the display size is, the larger the amount of contour compensation effect is, and the edge portion of the image is emphasized.

(Vii) In the case of the information amount of the input image, the contour compensation is performed on the basis of a constant transmission rate (corresponding to each transmission rate of the image decoding / encoding unit 1) as the information amount of the input image decreases. The effect amount is increased and the edge portion of the image is emphasized.

(Viii) In the case of the discontinuity of the input image, when the discontinuity of the input image is detected, the contour compensation effect amount is minimized and the edge portion of the image is weakened as much as possible.

With the above configuration, at the time of decoding, the image signal received by the image decoding / encoding unit 1 is decoded by this image decoding / encoding unit 1, and then the decoded data is The edge portion of the image is emphasized by the contour compensation unit 2A with a predetermined contour compensation effect amount, and then displayed on the TV monitor 3A.

Further, at the time of encoding, the image signal obtained by the image pickup unit 5 is subjected to image decoding / encoding after the edge portion of the image is emphasized by the contour compensation unit 2A with a predetermined contour compensation effect amount. The image is output to the unit 1, encoded by the image decoding / encoding unit 1, and output.

At this time, in the present embodiment, the contour compensator 2A
The contour compensation effect amount in 4 is adaptively controlled by the contour compensation effect amount control unit 4 as described above in (i) to (viii) according to changes in the various system environment parameters,
The effect of contour compensation corresponding to changes in the system environment can be obtained.

When the contour compensation effect amount is set to be strong in accordance with the tendencies of the items (i) to (viii), the contour compensator 2A outputs the input signal as shown in FIG. As shown in (b), when the slope between the widths H is made steep and the edge portion is emphasized, the contour compensation effect amount is weakened according to the tendencies of the items (i) to (viii). Is shown in FIG.
The input signal as shown in (a) is output from the contour compensating section 2A as a signal having a gentle slope as shown in FIG. 3 (c).

That is, by adjusting the effect amount of the contour compensation, the image becomes blurred when the effect amount is small, and the image becomes clearer as the effect amount increases.

By utilizing such a principle of contour compensation, and further by taking advantage of the fact that even if the image is blurred due to the visual characteristics of human beings, it does not matter so much, in the present embodiment, for example, In the case of the items (7) and (vii), the amount of information generated from the image decoding / encoding unit 1 or the TV camera 5A is monitored under a constant transmission rate, and the By adaptively switching the contour compensation effect amount set in stages, block distortion noise due to DCT is reduced, and the image quality is significantly improved.

As described above, according to the method of this embodiment, the contour compensation effect amount in the contour compensation unit 2A is adaptively controlled by the contour compensation effect amount control unit 4 according to various system environment parameters, and the system By effectively utilizing the effect of contour compensation in response to changes in the environment, it is possible to significantly improve image quality.

In the above-described embodiment, the case where the method of the present invention is applied to both the case of decoding image data and the case of encoding image data has been described, but the present invention is applied only to either case. The method of the invention may be applied.

(B) Description of Second Embodiment Next, in the case of the above items (8) and (viii), that is, the case where the discontinuity of the input image is used as a system environment parameter, A configuration example will be described with reference to FIGS. 4 and 5.

FIG. 4 is a block diagram showing a second embodiment of the present invention, and FIGS. 5A and 5B are block diagrams showing an example of a detection circuit for detecting discontinuity of an input image. is there. In the figure, the same reference numerals as those used above indicate the same parts, and a description thereof will be omitted.

In FIG. 4, 5-1 to 5-n are TV cameras (imaging units) for obtaining image signals respectively. In this embodiment, n units are provided so that image signals of n channels can be obtained. There is.

Reference numeral 6 denotes a channel / resolution switching operation section for selecting and switching an n-channel image signal to be encoded and outputting a resolution switching instruction, and 7 denotes a channel / resolution switching operation section 7. It is a channel switching unit that selects and outputs any one of the image signals of the TV cameras 5-1 to 5-n according to an instruction.

Further, 8 is a resolution switching unit for switching the resolution of the image signal selected according to the instruction from the channel / resolution switching operation unit 7, and 9 is the image decoding / encoding unit 1.
Is a detection circuit for detecting the discontinuity of the input image to, that is, the switching operation by the channel switching unit 7 or the resolution switching unit 8.

The detection circuit 9 shown in FIG.
Alternatively, the one shown in FIG. 5B is used.

The detection circuit 9 shown in FIG. 5A is composed of two flip-flops (FF) 10 and 11 and an exclusive OR circuit (EOR) 12.

The flip-flops 10 and 11 perform a latch operation each time a frame pulse (one vertical frame pulse output for each frame is used) is input, and the flip-flop 10 is the latest channel. The flip-flop 11 latches the switching signal (or the resolution switching signal) and the output from the flip-flop 10, that is, the channel switching signal (or the resolution switching signal).

Further, the exclusive OR circuit 12 takes the exclusive OR of the output from the flip-flop 10 and the output from the flip-flop 11, so that when the previous signal and the current signal are different, That is, when there is a change in the channel switching signal (or resolution switching signal), the output is raised and the fact that the discontinuity of the input image has occurred is output to the contour compensation effect amount control unit 4 as a switching detection signal. It is a thing.

On the other hand, the detection circuit 9 shown in FIG. 5B has two flip-flops 13 and 14 and an exclusive OR circuit 15 for detecting a change in the channel switching signal.
Two flip-flops 16 and 17 and an exclusive OR circuit 18 for detecting a change in the resolution switching signal,
It is composed of an OR circuit (OR) 19 which ORs the outputs from the exclusive OR circuits 15 and 18.

A circuit formed by the flip-flops 13 and 14 and the exclusive OR circuit 15, a flip-flop 16 and
17 and the circuit formed by the exclusive OR circuit 18 perform exactly the same operation as the circuit described above with reference to FIG. 5A and detect changes in each signal (image discontinuity). Therefore, detailed description thereof will be omitted.

When either or both of the channel switching signal and the resolution switching signal change, the outputs of the exclusive OR circuits 15 and 18 rise, and the output of the OR circuit 19 rises accordingly, and the input image The fact that the discontinuity has occurred is output to the contour compensation effect amount control unit 4 as a switching detection signal.

The contour compensation effect amount control section 4 receiving the switching detection signal from the detection circuit 9 minimizes the contour compensation effect amount and weakens the edge portion of the image as much as possible.

As a result, the noise caused by the generation of a large amount of information immediately after the switching of the device having the channel switching function / resolution switching function is reduced, and the image quality can be improved.

[0060]

As described in detail above, according to the system environment adaptive contour compensation method of the present invention, the contour compensation effect amount in the contour compensation unit is adaptively controlled according to various system environment parameters. Since it is configured, the contour compensation effect corresponding to the change of the system environment can be obtained, and the display image quality and the image quality of the image data to be transmitted can be significantly improved.

[Brief description of drawings]

1A and 1B are block diagrams of the principle of the present invention.

FIG. 2 is a block diagram showing a first embodiment of the present invention.

3 (a) to 3 (c) are diagrams showing examples of waveform changes according to the contour compensation effect amount.

FIG. 4 is a block diagram showing a second embodiment of the present invention.

5A and 5B are block diagrams each showing an example of a detection circuit for detecting discontinuity of an input image.

FIG. 6 is a block diagram showing a conventional example.

[Explanation of symbols]

1 Image decoding / encoding unit 1A image decoding unit 1B image coding unit 2A contour compensation section 3 Image display section 3A TV monitor (image display section) 4 Contour compensation effect amount control unit 5 Imaging unit 5A, 5-1 to 5-n TV camera (imaging unit) 6-channel / resolution switching operation unit 7 channel switching unit 8 Resolution switching section 9 Detection circuit 10,11 flip-flops 12 Exclusive OR circuit 13,14 flip-flops 15 Exclusive OR circuit 16,17 flip-flops 18 Exclusive OR circuit 19 OR circuit

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yuichi Terui             1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture             Within Fujitsu Limited (72) Inventor Toshihiro Yamanaka             3-22-8, Hakata Station, Hakata-ku, Fukuoka City, Fukuoka Prefecture             Issue Fujitsu Kyushu Digital Technology Co., Ltd.             Inside the company (72) Inventor Kenji Rikimaru             3-22-8, Hakata Station, Hakata-ku, Fukuoka City, Fukuoka Prefecture             Issue Fujitsu Kyushu Digital Technology Co., Ltd.             Inside the company (72) Inventor, Takashi Kawabata             1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture             Within Fujitsu Limited

Claims (7)

[Claims] 1. An image decoding unit (1, 1A) for decoding an image signal and an image edge corresponding to a contour compensation effect amount for decoded data obtained by the image decoding unit (1, 1A). A contour compensating unit (2A) for emphasizing a portion, and an image display unit (3, 3) for displaying an image based on the decoded data in which the edge portion of the image is emphasized by the contour compensating unit (2A).
The contour compensator (2A)
The system-environment-adaptive contour compensation method, characterized in that the contour compensation effect amount is controlled in accordance with a system environment parameter. 2. An image pickup unit (5, 5A, 5-) for obtaining an image signal.
1-5-n) and the imaging unit (5, 5A, 5-1-5-)
Contour compensation unit (2A) for enhancing the image edge portion according to the contour compensation effect amount for the image signal obtained in n).
And an image coding unit (1, 1B) for coding an image signal in which the edge portion of the image is emphasized by the contour compensation unit (2A), the contour compensation unit (2A) A system environment adaptive contour compensation method characterized in that the contour compensation effect amount is controlled according to the system environment parameter. 3. The transmission rate is used as the system environment parameter, and the higher the transmission rate, the greater the amount of the contour compensation effect, and the edge portion of the image is emphasized. The system environment adaptive contour compensation method according to claim 2. 4. The pixel thinning rate is used as the system environment parameter, and the lower the pixel thinning rate is, the larger the contour compensation effect amount is to emphasize the edge portion of the image. 3. The system environment adaptive contour compensation method according to claim 1 or 2. 5. A moving image or a still image is used as the system environment parameter. When the image is a still image, the contour compensation effect amount is increased to emphasize the edge portion of the image, If it is, the contour compensation effect amount is reduced to weaken the enhancement of the edge portion of the image, and the system environment adaptive contour compensation method according to claim 1 or 2. 6. An information amount of an input image is used as the system environment parameter, and the edge compensation effect amount is increased as the information amount of the input image is reduced on the basis of a constant transmission rate, and an edge portion of the image is detected. The system environment adaptive contour compensation method according to claim 1, wherein the contour compensation method is emphasized. 7. The discontinuity of the input image is used as the system environment parameter, and when the discontinuity of the input image is detected, the contour compensation effect amount is reduced to reduce the edge portion of the image. The system environment adaptive contour compensation method according to claim 1 or 2, wherein the emphasis is weakened.