JPH0410774A - Outline correcting device - Google Patents

Abstract

PURPOSE:To execute outline correction corresponding to the level of an input signal and to always obtain optimum picture quality by varying the level of an outline emphasizing signal in accordance with the level of a video signal. CONSTITUTION:An inputted video signal is supplied to an adjusting circuit 1, the lightness and contrast of the video signal are adjusted, the adjusted video signal A is applied to a non-linear circuit 15 and a delay circuit 3, and a delayed video signal F is supplied to an adder 5. Namely, a signal (low signal level) indicating the dark part of an image out of the video signal outputted from the circuit 15 and a signal (high signal level) indicating the light part of the image are compressed at their signal levels and the signal level of a signal indicating the intermediate light part of the image is extended. An outline signal E supplied from an outline signal forming circuit 2 is added to the video signal F delayed by a prescribed time through the circuit 3 by the adder 5. Consequently, the outline-emphasized video signal G is outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a contour correction device in a video signal processing circuit of a television receiver.

[Prior Art] Conventionally, as methods for improving the image quality of television receivers, methods for improving image quality based on the frequency characteristics of a video amplification circuit and a delay-type contour correction circuit method have been adopted.

FIG. 3 shows an example of the basic configuration of a conventional contour correction circuit.

In FIG. 3, the manually input resolution signal is supplied to a contour signal forming circuit 2 and a delay circuit 3 after its brightness and contrast are adjusted in a bright contrast adjusting circuit 1.

The contour signal forming circuit 2 extracts a signal corresponding to the contour of the image represented by the input video signal and supplies it to the gain control circuit 4 at the subsequent stage.

The gain control circuit 4 is configured to control the gain of the contour signal supplied by operating an operation section (not shown), and the contour signal whose gain has been controlled is sent to the adder 5.
supplied to

On the other hand, the adder 5 is supplied with the video signal whose brightness and contrast have been adjusted in the bright contrast adjustment circuit 1 after being delayed by a predetermined time by the delay circuit 3.
The adder 5 adds the contour signal supplied from the gain control circuit 4 and the video signal supplied from the delay circuit 3, so that the adder 5 outputs a contour-corrected video signal. .

Moreover, FIG. 4 is a diagram showing an example of the configuration of the horizontal contour correction circuit.
FIG. 5 is a diagram showing signal waveforms at each part of the configuration of FIG. 4.

In FIG. 3, the video input signal (A) is transmitted to delay circuits 7 and 1.
0, 13, coefficient multipliers 6, 8, 11, adders 9, 12 .
14, a video signal output to which a contour signal is added as shown in FIG. 5(G) is obtained.

[Problems to be Solved by the Invention] In the conventional contour correction circuit described above, when a certain amount of correction is set, the same amount of contour correction is performed regardless of the size of the video signal (bright areas, dark areas). If it is emphasized too much, the edge enhancement becomes noticeable in dark scenes, resulting in a glaring image.

Furthermore, when white characters or the like are displayed in a bright scene, the cathode ray tube enters a blooming state, causing a phenomenon of whitewashing.

In view of the above-mentioned problems, the present invention aims to always obtain optimum image quality by performing contour correction according to the level of a human input signal.

[Means for Solving the Problems] The contour correction device of the present invention includes a nonlinear circuit that compresses dark and bright portions of a video signal and expands a video signal with medium brightness, and an output signal of the nonlinear circuit. The apparatus includes a contour signal forming circuit for forming a contour signal, a delay circuit for timing the video signal with the contour forming circuit, and an adder for adding the contour forming signal and the delayed video signal.

[Function] With the above configuration, the level of the edge enhancement signal is varied according to the size of the video signal, suppressing glare in dark scenes and blooming in bright scenes, while also performing sufficient edge enhancement on the video signal to create sharpness. It is possible to project an image with a certain amount on the display screen.

[Example] Hereinafter, the present invention will be explained using examples of the present invention.

FIG. 1 is a diagram showing the configuration of a contour correction circuit as an embodiment of the present invention. In FIG. 1, 1 is a brightness and contrast adjustment circuit, 2 is a contour signal forming circuit, 3 is a delay circuit, 5 is an adder, and 15 is a nonlinear circuit.

In FIG. 1, an input video signal is supplied to a brightness control (brightness adjustment and contrast (video signal level adjustment) adjustment circuit 1, where the brightness and contrast are adjusted. The adjusted video signal A is applied to the nonlinear circuit 15 and the delay circuit 3, and the video signal F delayed by the delay circuit 3 is supplied to the adder 5.

Now, assume that the nonlinear circuit 15 has nonlinear characteristics as shown in FIG. 2(A), and that a video signal having a stepped waveform as shown in FIG. 2(B) is supplied to the nonlinear circuit 15. , the nonlinear circuit 15 outputs a video signal having a waveform as shown in FIG. 2(C).

The video signal output from the nonlinear circuit 15 is shown in FIG. 2(C).
As shown in , the signal level is compressed for the signal indicating the dark part of the image (where the signal level is low) and the signal indicating the bright part of the image (where the signal level is high), and the signal level is compressed for the part where the brightness of the image is intermediate. (signal level is around the middle)
The signal level will be expanded.

Then, the video signal as shown in FIG. 2(C) is supplied to the contour signal forming circuit 2, and the contour signal forming circuit 2 outputs the contour signal E as shown in FIG. 2(D). Supply to 5.

The adder 5 receives the contour signal E supplied from the contour signal forming circuit 2 and the video signal F delayed by a predetermined time by the delay circuit 3.
By adding these, a video signal G with contour enhancement as shown in FIG. 2(E) is output.

As described above, by providing the nonlinear circuit 15 in front of the contour signal forming circuit 2, the amount of contour enhancement for signals representing dark and bright parts of the image is suppressed, and a wide range from dark to bright scenes of the image is suppressed. It is possible to perform optimal edge enhancement in dark scenes, prevent glare in dark scenes, blooming (defected whites, blurring) in bright scenes, etc. You will be able to get contour enhancement.

The configuration of the contour signal forming circuit 2 in FIG. 1 is the same as that in FIG. 3 described above.

Another example will be shown.

Other embodiments of the present invention will be described below.

FIG. 6 is a diagram showing the configuration of a contour correction circuit as another embodiment of the present invention. In FIG. 6, 15 is a nonlinear circuit;
20 is an amplifier, 21.23 is a differential circuit, 22 is an inverting amplifier, 24 is a delay circuit, and 25 is an adder.

In Fig. 6, video input signal A (see Fig. 7 (B))
is a nonlinear circuit 1 having characteristics as shown in FIG. 7(A).
After the signal waveform becomes as shown in Fig. 7(C) by 5,
After being amplified by the amplifier 20 (contour signal forming circuit 26 composed of differentiating circuits 21 and 23 and inverting amplifier 22), a signal having a waveform as shown in FIG. 7(E) is formed.

On the other hand, after the human input video signal A is delayed by the delay circuit 24,
It is supplied to an adder 25.

As described above, the output signal M of the contour signal forming circuit 26 (see FIG. 7(E)) and the output signal N of the delay circuit 24 (see FIG. 7(F))
) is supplied to the adder 25, and by adding the two, a video signal P (see FIG. 7(G)) which has been subjected to contour correction processing is obtained. As shown in FIG. 7(G), according to this embodiment, overshoot (c in the figure) and preshoot (b in the figure) are added to the human-powered video signal to obtain a video signal with even better sharpness. I can do it.

[Effects of the Invention] As explained above, in the contour correction method for improving the image quality of television receivers, the apparent image quality deterioration caused by changes in the magnitude of the video human input signal, such as contour correction in dark scenes. Suppresses over-emphasis and blooming phenomena in bright scenes,
Furthermore, since dynamic contour correction such as sufficient contour enhancement is automatically performed in normal cases, it is possible to always obtain a good video signal.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a contour correction circuit as an embodiment of the present invention. FIG. 2 is a diagram showing signal waveforms at various parts of the circuit shown in FIG. 1. FIG. 3 is a diagram showing an example of the configuration of a conventional contour correction circuit. FIG. 4 is a diagram showing an example of the configuration of a horizontal contour signal correction circuit. FIG. 5 is a diagram showing signal waveforms at various parts in the configuration of FIG. 4. FIG. 6 is a diagram showing the configuration of a contour correction circuit as another embodiment of the present invention. FIG. 7 is a diagram showing signal waveforms flowing through each part of the circuit shown in FIG. 6. 1...Bright contrast adjustment circuit 2...Contour signal forming circuit 3 710.13.24...Delay circuit 4...Gain control 5 9 12.14.25...Adder 6 8 11.
20...Amplifier 5...Nonlinear circuit 1.23...Differentiating circuit 2...Inverting amplifier 5...Addition circuit (A) (C and

Claims (1)

[Claims] In the video amplification circuit of a television receiver, a nonlinear circuit compresses the dark and bright parts of the video signal and expands the video signal with medium brightness, and a limbal signal is generated from the output signal of the nonlinear circuit. A contour comprising a limbal signal forming circuit for forming a contour, a delay circuit for timing the video signal with the limbus forming circuit, and an adder for adding the contour forming signal and the delayed video signal. correction device.