JPH02168784A - Cross color suppression circuit - Google Patents

Abstract

PURPOSE:To suppress cross color and to improve the quality of picture by extracting a pseudo color signal and a color signal crosstalk component from a luminance signal with a band pass filter and using a band elimination filter so as to eliminate the extracted color signal crosstalk component. CONSTITUTION:A band pass filter 7 is used having the same characteristic as that of a band pass filter 2 to extract a pseudo color signal component included in a luminance signal (b). Moreover, a band elimination filter 8 eliminates the component in crosstalk with the color signal (c) near 3.58MHz onto the luminance signal (b). Then the signal is rectified by a rectifier circuit 9 and only the low level signal is eliminated by a base clip circuit 10 and a level adjustment circuit 11 adjusts it into a proper level. Thus, a color amplification factor of a color signal amplifier circuit 5 is set. Thus, in the presence of a pseudo color signal, the color amplification factor of the color signal amplifier circuit 5 is decreased to suppress the level of the cross color thereby suppressing the deterioration in the picture quality.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applied to a YC separation circuit that separates a luminance signal and a chrominance signal from an NTSC combo video signal of a television receiver or VTR. The present invention relates to a cross color suppression circuit that improves cross color interference caused by cross color.

BACKGROUND OF THE INVENTION In recent years, YC separation using a line comb filter has become common as a method for widening the bands of luminance signals and color signals in order to improve image quality.

FIG. 2 is a block diagram showing a conventional YC separation circuit and its peripheral circuit configuration. In FIG. 2, a composite video signal a is separated into a luminance signal and a color signal C by a YC separation circuit 1 and a bandpass filter 2. The luminance signal is sent to the matrix circuit 4 via the luminance signal processing circuit 3. Further, the color signal C is sent to the matrix circuit 4 via the color signal amplification circuit 5 and the color demodulation circuit 6, which are controlled by the color amplification control voltage d, and is mixed with the luminance signal by 7 matrix in the matrix circuit 4. These become G and B signals. The YC separation circuit 1 uses a line comb filter. That is, for the luminance signal, the correlation between the current signal and the signal one line before is strong and almost equal, and for the color signal, the polarity of the current signal and the signal one line before is reversed. The color signal is separated from the composite video signal by subtracting the signal of the current line from the signal of the previous line.

Problems to be Solved by the Invention However, in the above-mentioned conventional configuration, when there is no line correlation in the luminance signals, the separation method by subtracting the signals of the previous and succeeding lines causes crosstalk between the luminance signals and the color signals. There is a problem in that this causes interference and significantly deteriorates the image quality. For example, if a live image is displayed on a black and white gray scale 1 in a preview image, colored gray may occur.

The present invention solves the above-mentioned conventional problems, and provides a cross-color suppression circuit capable of suppressing Taloscal interference from increasing even when a luminance signal talks to a color signal, thereby suppressing image quality deterioration. The purpose is to

Means for Solving the Problems In order to solve the above problems, the cross color suppression circuit of the present invention includes a bandpass filter that extracts a pseudo color signal and a color signal crosstalk component from a luminance signal, and a bandpass filter that extracts a color signal crosstalk component from the extracted signal. - a band elimination filter that removes color components, a rectifier circuit that rectifies the pseudo color signal and extracts it as a control signal, and a synthesis circuit that combines the control signal with a color amplification control voltage to set the color amplification degree. 17 to reduce the color amplification degree when there is a false color signal.
It is configured to suppress scalars.

Effect With the above configuration, the bandpass filter extracts the pseudo color signal and color signal crosstalk components from the luminance signal, and the band elimination filter removes the color signal crosstalk components from the signal extracted by the bandpass filter. After obtaining a false color signal and rectifying it with a rectifier circuit, only the signal with a high level is taken out with a base clip circuit and used as a control signal, and this control signal is adjusted to an appropriate level with a level adjustment circuit as necessary. Change it to
This is combined with the color amplification control voltage in a subtraction circuit to set the color amplification, and when there is a false color signal, the color amplification is lowered and cross color is suppressed. Even if the signal is less than 1, the cross color disturbance is suppressed from becoming large, and the deterioration of image quality is suppressed.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a YC separation circuit using a cross color suppression circuit according to an embodiment of the present invention and its peripheral circuit configuration. Reference numerals are given and explanations thereof are omitted. In Figure 1, 7 is 3.58 of the bandpass filter 2 and the rotation e.
This is a bandpass filter of t4Hz±I HN3, which extracts the pseudo color signal and color signal crosstalk components from the luminance signal. Reference numeral 8 denotes a band elimination filter, which removes the color signal cross 1 to - 3 components from the signal extracted by the band pass filter 7. For example, 3.58H11z
0.4MHz. 9 is a rectifier circuit that rectifies the pseudo color signal. Reference numeral 10 denotes a base clip circuit, which extracts only a signal with a high level from the rectified signal as a control signal. A level adjustment circuit 11 changes the output of the base clip circuit 10 to an appropriate level. Reference numeral 12 denotes a subtraction circuit, which sets the color amplification degree of the color signal amplification circuit 5 by subtracting the control signal output from the level adjustment circuit 11 from the color amplification degree control voltage d.

The cross color suppression circuit 13 is configured by the above (2).

The operation of the above configuration will be described below.

In FIG. 1, when the luminance signal of the composite video signal a is No. 18, which is different from the luminance signal of one horizontal line before, the YC separation circuit 1 cannot separate it, and the color signal C cross 1-1 is generated. The crosstalk signal not removed by the bandpass filter 2 is a false color signal, that is,
It becomes a cross color.

On the other hand, a band-pass filter 7 having the same characteristics as the band-pass filter 2 is used to extract the pseudo-color signal component contained in the luminance signal l), and further, C:1-':y:Limination B77 Ilter8 Te3. 58Hz NJ 3 Cata) After removing crosstalk components from the color, +1<C or luminance signals, the rectifier circuit rectifies the signals, and the base flip circuit 10 converts the signals into low-level signals only. Remove.

Furthermore, after adjusting the signal to an appropriate level in the level adjustment circuit 11, this signal is subtracted from the color amplification control voltage d in the subtraction circuit 12 to obtain a new color II! 1st order control matter 11th d
′ is obtained. This sets the color amplification degree of the color (F's-""j amplification circuit. Therefore, if there is a pseudo O,) color signal, the color amplification degree of the color signal amplification circuit 5 is set to 1. ·debt,
The level of cross color is suppressed, and deterioration of image quality is suppressed.

Incidentally, the band elimination filter 8 prevents the circuit from malfunctioning due to the cross of the luminance signal M/\ when there is a regular color signal.

Furthermore, the base clip circuit 11 prevents this circuit from malfunctioning due to noise.

Effects of the Invention As described above, according to the present invention, when there is a false color signal in the luminance signal, the color amplification degree of the color signal is adjusted so that even if the luminance signal crosstalks with the color signal, cross color interference will not become large. It is possible to suppress cross color by lowering the ratio, and the image quality can be significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a YC separation circuit using a cross color suppression circuit in an embodiment of the present invention and its peripheral circuit configuration, and FIG. 2 is a block diagram showing a conventional Ye separation circuit and its peripheral circuit configuration. It is a diagram. 7... Band pass filter, 8... Band elimination filter, 9... Rectifier circuit, 10... Base clip circuit, 11... Level adjustment circuit, 12...
Subtraction circuit, 13...Cross color suppression circuit, b...
Luminance signal, C...color signal, d, d'...color amplification control voltage. Agent Yoshihiro Morimoto

Claims (1)

[Claims] 1. A band pass filter that extracts a pseudo color signal and color signal crosstalk components from a luminance signal, a band elimination filter that removes the color signal crosstalk components from the extracted signal, and a control unit that rectifies the pseudo color signal. A rectifier circuit that extracts the signal as a signal, and a synthesis circuit that combines the control signal with a color amplification control voltage to set a color amplification degree, and when the false color signal is present, the color amplification degree is lowered to create a cross color. Cross color suppression circuit configured to suppress.