JPH05260502A - Video signal processing circuit - Google Patents

Abstract

PURPOSE:To reproduce an excellent image by reducing streaking of a false horizontal outline emphasising signal and a large amplitude signal generated in a start part and an end part of a horizontal video signal, in the case of reflecting correctly a signal of a conventional aspect ratio, in a High Vision television set and a wide screen television set. CONSTITUTION:From a scan converting circuit 11, a signal period pulse (f) for showing a video signal period is obtained and a control pulse (g) corresponding to a horizontal video start part and its end part is generated, and by this control pulse (g), an adjustment control circuit 15 is controlled. In such a way, streaking of a false and unseemly output emphasizing signal and a large amplitude signal generated in the start part and the end part of a horizontal video signal can be reduced, and an excellent image can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal processing circuit for reducing the unsightly appearance at the boundary between a video signal portion and a non-signal portion of a high-definition television receiver or a wide television receiver.

[0002]

2. Description of the Related Art In recent years, high-definition television receivers and wide-screen television receivers have begun to be put on the market, and wide screens are receiving attention as future television receivers.

A video signal processing circuit of a conventional wide television receiver will be described below with reference to the drawings. Television signals currently being broadcast are
The aspect ratio is 3: 4, and the high-definition signal has a wide screen with an aspect ratio of 9:16. Therefore, a cathode ray tube (hereinafter, abbreviated as CRT) has a wide aspect ratio of 9:16.
Wide television receivers using the same have been commercialized. In this case, in order to correctly display a conventional television signal on a 9:16 CRT, it is necessary to scan-convert the signal so that the aspect ratio is 3: 4 on the television screen. As shown in FIG. 3, a video signal processing circuit of a conventional wide television receiver receives an input luminance signal a and an input color difference signal b and obtains a converted luminance signal c, a converted color difference signal d, and an output luminance signal e. .. In addition, the scan conversion circuit 11,
It is composed of a horizontal contour enhancement circuit 12 and an RGB processor 13.

With respect to the video signal processing circuit having the above components, the relationship and operation of each component will be described below with reference to FIG.
A description will be given using (a) and (b). First, the input luminance signal a is converted into an appropriate signal by the scan conversion circuit 11 (4/3 when converting from 3: 4 to 9:16).
Times) to obtain the converted luminance signal c. The input color difference signal b is also converted into an appropriate signal by the scan conversion circuit 11 like the luminance signal,
The converted color difference signal d is obtained. These converted signals include
It is easy to see that there are no signal parts. Next,
The contour of the converted luminance signal c is emphasized by the horizontal contour emphasizing circuit 12 to obtain an output luminance signal e. At this time, unsightly and undesirable false contours are emphasized and generated at the horizontal start portion and the end portion of the luminance signal. The output luminance signal e and the converted color difference signal d are appropriately controlled by the RGB processor 13 in the subsequent stage, such as the contrast of the luminance signal and the saturation of color, and drive the CRT.

[0005]

However, in the above-mentioned conventional configuration, a false horizontal contour enhancement signal or streaking due to the influence of a large amplitude signal occurs at the boundary between the video signal portion and the non-signal portion, resulting in an unsightly image. Had a problem.

The present invention solves the above-mentioned conventional problems and reduces an unsightly signal such as false horizontal contour enhancement signal or streaking generated at a horizontal start portion and an end portion of a video signal to obtain a preferable image. An object is to provide a video signal processing circuit.

[0007]

In order to achieve the above object, a video signal processing circuit of the present invention includes a control pulse generating circuit for generating a signal corresponding to a start portion to an end portion of a video signal in a scan conversion output signal. The control pulse thus generated appropriately controls the contrast of the luminance signal and the saturation of the color.

[0008]

According to the present invention, in the above structure, the contrast of the luminance signal and the saturation of the color are continuously reduced at the horizontal start portion and the end portion of the image to suppress the generation of unsightly false contours and streaking. Become.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, the same components and signal names as in FIG. 3 of the conventional example are given the same reference numerals. As shown in FIG. 1, the video signal processing circuit of the present embodiment is composed of a scan conversion circuit 11, a horizontal contour emphasis circuit 12, an RGB processor 13, a control pulse generation circuit 14, and an adjustment control circuit 15. The converted luminance signal c of the scan conversion circuit 11 is the horizontal contour enhancement circuit 1
2, the converted color difference signal d is directly sent to the RGB processor 13
Entered in. Further, the scan conversion circuit 11 supplies a signal period pulse f indicating a video signal period to the control pulse generation circuit 14, and the output control pulse g is supplied to the control input of the adjustment control circuit 15.

Regarding the video signal processing circuit having the above components, the relationship and operation of the components will be described using the signal waveforms in FIG. First, the input luminance signal a is supplied to the scan conversion circuit 11 and appropriately converted to obtain the converted luminance signal c. In addition, a signal period pulse f indicating a video signal period is supplied from the scan conversion circuit 11 to the control pulse generation circuit 14 in the subsequent stage, and a control pulse g is obtained. The converted luminance signal c has its contour emphasized by the horizontal contour emphasizing circuit 12 to obtain an output luminance signal e. The input color difference signal b is also appropriately converted by the scan conversion circuit 11, and together with the output luminance signal e, the RGB processor 1 in the subsequent stage.
3 and adjusts the contrast of the luminance signal and the saturation of the color by the output of the adjustment control circuit 15 appropriately. A control pulse g is input to the adjustment control circuit 15, and at the horizontal start portion and the end portion of the video signal, the adjustment value m obtained by continuously lowering the contrast of the luminance signal from the original adjustment is obtained and added to the RGB processor 13. ing. The controlled luminance signal n of the output signal is improved to a signal in which false contours and large amplitude signals are suppressed. Similar processing is performed for the color saturation.

[0012]

As is apparent from the above embodiments, according to the present invention, a control pulse corresponding to a horizontal image start portion to a horizontal image portion, and with this pulse, the contrast of the luminance signal and the saturation of the color are appropriately adjusted. By providing a means for controlling,
It is possible to realize an excellent video signal processing circuit that can reduce unsightly false contour enhancement signals and streaking of large-amplitude signals that occur at the start and end of a horizontal video signal.

[Brief description of drawings]

FIG. 1 is a block diagram of a video signal processing circuit according to an embodiment of the present invention.

FIG. 2 is a signal waveform diagram of the video signal processing circuit in the embodiment.

FIG. 3A is a block diagram of a conventional video signal processing circuit, and FIG. 3B is a signal waveform diagram of a conventional video signal processing circuit.

[Explanation of symbols]

 11 Scan Conversion Circuit 12 Horizontal Edge Enhancement Circuit 13 RGB Processor 14 Control Pulse Generation Circuit 15 Adjustment Control Circuit

Claims (1)

[Claims] 1. A means for displaying a video signal in a range narrower than an image display range of a cathode ray tube, a means for adjusting the contrast and color saturation of a luminance signal, and a horizontal start portion and an end portion of the video signal. A video signal processing circuit having means for generating the control pulse, and means for controlling the contrast and color saturation of the luminance signal by the control pulse.