JPH05122557A - Contour correction circuit - Google Patents

Abstract

PURPOSE:To prevent a natural feeling from being damaged by controlling the definition of an image damaging the natural feeling of an image by increasing the definition even when such an image is contained. CONSTITUTION:This circuit is provided with a contour signal generation circuit 2 to generate a contour signal from a video signal to be inputted, contour signal control circuit 3 to increase/decrease the amplitude of the contour signal based on the video signal, delay circuits 4 to delay the input signal for prescribed time, and mixers 5 to mix outputs from the contour signal control circuit 3 and the delay circuits 4. By mixing the contour signal controlled by a control signal to increase/decrease the amplitude of the contour signal by judging the color of the input video signal concerning the contour signal extracted from the input video signal and the time-delayed video signal, the contour-corrected video signal is outputted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contour correction circuit for correcting a contour of an image by correcting or enhancing a high frequency component in a video signal.

[0002]

2. Description of the Related Art When a frequency characteristic of a video signal in a high frequency band is insufficient, it is observed that details cannot be expressed in a reproduced image or that the image itself is blurred. Therefore, conventionally, high frequency components of the video signal,
That is, a means is used in which the contour signal of the video signal is extracted and added to the original video signal to correct the characteristics in the high frequency range. However, if the extracted contour signal is added to the original video signal as it is, there are cases where the natural feeling of the image is impaired, high-frequency noise is emphasized, and the like, which causes various problems.

In order to solve these problems, a coring process is performed in which all minute contour signals are regarded as noise and removed. For contour signals with large amplitude, an upper limit value is set for the amplitude, and all amplitudes above the upper limit value are set. It has been conventionally performed that the contour signal is added to the original video signal after performing some processing on the contour signal such as clipping processing of replacing with the upper limit value.

[0004]

However, when the contour correction is performed without distinguishing the conventional images as described above, for example, when there are a person and a building in the screen, the contour signal amount is determined with the building as a reference. Then, human skin stains are emphasized, and there is a problem that the natural feeling of the image is significantly impaired depending on the degree of contour correction.

The present invention solves the above-mentioned conventional problems. When increasing the sharpness of a plurality of images, attention is paid to the colors of the respective images, and the sharpness of each image is changed. An object of the present invention is to provide a contour correction circuit which does not impair favorable sensitivity.

[0006]

The contour correction circuit of the present invention is a contour signal generating means for generating a contour signal from an input video signal, and contour signal control for increasing or decreasing the amplitude of the contour signal based on the video signal. Means, delay means for delaying the input signal for a predetermined time, and mixing means for mixing the output from the contour signal control means and the delay means.

[0007]

With the above-described structure, the contour correction circuit of the present invention controls the amplitude of the contour signal for an image which is unnatural when the sharpness is increased by performing the contour correction similarly to the surrounding image. Prevents loss of feeling.

The contour correction circuit of the present invention can perform contour correction by controlling the amplitude of the contour signal of an arbitrary image within the screen, from the viewpoint other than preventing the loss of naturalness. ..

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic block diagram of a contour correction circuit according to an embodiment of the present invention. In FIG. 1, 1a, 1b and 1c are input terminals to which a video signal is input, 2 is a contour signal generation circuit which generates a contour signal from the video signals input to the input terminals 1a, 1b and 1c, and 3 is an input. The contour signal control circuits 4a, 4b, and 4c that determine the color of the video signal input from the terminals 1a, 1b, and 1c and increase or decrease the amplitude of the contour signal generated in the contour signal generation circuit 2 according to the determination result are The delay circuits 5a, 5b and 5c for delaying the video signal by the signal delay time in the contour signal generation circuit 2 and the contour signal control circuit 3 are outputs from the contour signal control circuit 3 and outputs from the delay circuits 4a, 4b and 4c. Mixers 6a, 6b, 6c for mixing
It is an output terminal of the contour correction circuit for outputting the signals from a, 5b and 5c to the outside of the contour correction circuit.

FIG. 2 shows an example of the configuration of the contour signal control circuit 3 shown in FIG. In FIG. 2, 7a, 7
b and 7c are input terminals 1a, 1b and 1 of (FIG. 1), respectively.
An input terminal connected to c for inputting a video signal input to the contour correction circuit, a color ratio setting circuit 8 for setting a ratio of the video signal, and a video signal 9 set in the color ratio setting circuit 8. To the input terminals 7a, 7b, 7c
A color determination circuit for determining whether or not a video signal input from is applied, a control amount setting circuit for setting which control amount is applied to the determination result of the color determination circuit 9, and a set value of the control amount setting circuit 10. In accordance with the above, the control amount conversion circuit for applying the control amount to the judgment result of the color judgment circuit 9, 12 is an input terminal to which the contour signal from the contour signal generation circuit 2 of (FIG. 1) is input, and 13 is an input terminal 12. A delay circuit for delaying the input contour signal by time, a delay circuit 14 for delaying the signal for controlling the contour signal from the control amount conversion circuit 11, and a multiplier 15 for multiplying the signals of the delay circuit 13 and the delay circuit 14. The multiplier 16 is an output terminal for outputting the signal from the multiplier 15.

FIG. 3 is a diagram showing the signal waveform in each part of (FIG. 2). While using the following (FIG. 3) together, the video signals 7a, 7b, 7c have a ratio of 2: 2: 1. The circuit operation of FIG. 2 will be described for the case where the condition is set such that the amplitude of the contour signal is halved at that time and the amplitude of the contour signal is not changed at other times.

Signals (a), (b) and (c) are video signals input to the contour correction circuit. The color ratio setting circuit 8 sets the ratio 2: 2: 1 of the video signals (a), (b), and (c), and when the control amount is 2: 2: 1, the ratio is 0.5.
Otherwise, 1 is set by the control amount setting circuit 10. The output signal of the color determination circuit 9 is HIGH when 2: 2: 1 and is LOW except 2: 2: 1. (Figure 3)
In the range A, the ratio of the video signals (a), (b) and (c) is 1: 1: 1. Therefore, the color determination circuit 9 outputs a LOW signal and the control amount conversion circuit 11 outputs 1. To be done.
In the range B of (FIG. 3), the video signals (a), (b), (c)
Ratio is 2: 2: 1, the color determination circuit 9 outputs HI
The GH signal is output, and the control amount conversion circuit 11 outputs 0.5
Is output. Therefore, the signal (e) is obtained as the control signal.

Further, in the contour signal generating circuit 2 (FIG. 1),
It is assumed that the contour signal shown in (f) of FIG. 3 is generated from the video signal (a) or (b). The delay circuits 13 and 14 match the time delay amounts of the contour signal (f) and the control signal (e). Contour signal (f) with time delay
And the control signal (e) are multiplied by the multiplier 15, a contour signal (g) whose amplitude is controlled is obtained. That is, as a result, it is possible to obtain a contour signal in which the amplitude is halved when the video signals 7a, 7b, and 7c have a ratio of 2: 2: 1, and otherwise the amplitude does not change.

As described above, according to the present embodiment, as with the surrounding image, when the contour correction is performed to increase the sharpness and the naturalness is impaired, the amplitude of the contour signal is controlled to control the naturalness of the image. Prevent damaging.

An allowable range is provided for the ratio of the video signal, for example, by expanding the range of the video signal (a) to (a) :( b) :( c) = 2 to 3: 2: 1. You can also In addition to preventing the loss of the natural feeling, it is possible to perform the contour correction by controlling the amplitude of the contour signal of the arbitrary image on the screen.

[0016]

As described above, according to the present invention, when the contour correction is performed to increase the sharpness as in the surrounding image, the natural feeling is impaired. It has the effect of preventing damage.

The contour correction circuit of the present invention can perform contour correction by controlling the amplitude of the contour signal of an arbitrary image within the screen from the viewpoint other than preventing the loss of naturalness. ..

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a contour correction circuit according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a contour signal control circuit of the contour correction circuit.

FIG. 3 is a signal waveform diagram of each part of (FIG. 2)

[Explanation of symbols]

 1a-c input terminal 2 contour signal generation circuit 3 contour signal control circuit 4a-c delay circuit 5a-c mixer 6a-c output terminal 7a-c input terminal 8 color ratio setting circuit 9 color determination circuit 10 control amount setting circuit 11 Control amount conversion circuit 12 Input terminal 13 Delay circuit 14 Delay circuit 15 Multiplier 16 Output terminal

Claims (2)

[Claims] 1. A contour signal generating means for generating a contour signal from an input video signal, a contour signal control means for increasing or decreasing the amplitude of the contour signal based on the video signal, and a delay for delaying the input signal for a predetermined time. A contour correction circuit comprising: means, and means for mixing the contour signal control means and the output from the delay means. 2. A contour signal control means, a color ratio setting means for setting a color of the video signal by setting a ratio of the video signal, and a color judging means for judging whether the video signal is applicable to the color. 2. The contour correction circuit according to claim 1, wherein the contour signal is controlled by a control amount conversion unit that replaces the output of the color determination unit with a contour signal control signal amount.