JPH03291090A - High saturation picture frequency correction device - Google Patents

Abstract

PURPOSE:To always attain contour emphasis of a high saturation picture by comparing polarity of a high frequency component of a correction signal with polarity of a high frequency component of a luminance signal and selecting the correction signal or the inverted correction signal depending on the result of comparison. CONSTITUTION:A matrix circuit 4 generates a luminance signal (b) and a correction signal (c) in response to inputted R, G, B signals and a high frequency component (i) and a correction contour signal (d) of the high frequency component of respective signals from HPF 21, 5 are outputted, the polarities are compared by a polarity comparator circuit 22 and a selection circuit 24 is controlled in response to the result of comparison. Thus, a signal via a gain control circuit 6 and a noise slice circuit 7 and a signal via a polarity inversion circuit 23 are selected and outputted and added to the signal (b) by an adder 8. Through the constitution above, contour is emphasized always to a high saturation picture in an excellent way independently of the inversion and noninversion of correction signal change and luminance signal change.

Description

DETAILED DESCRIPTION OF THE INVENTION 3. Field of Industrial Application The present invention relates to a high chroma image frequency corrector for improving the sharpness of images with particularly high chroma obtained from television signals and the like.

BACKGROUND OF THE INVENTION Conventional high-chroma image frequency correctors include a method that adds each color difference signal and adds its contour signal component to a luminance signal (for example, Haruo Sakata, ”, Journal of Telecommunications Society VOL 34.
NO2, 1980).

A conventional high chroma image frequency corrector will be explained based on the block diagram of FIG.

A conventional high-chroma image frequency corrector uses R (red) signal a, G (green) signal, and B (blue) signal processed by a process circuit.
A matrix circuit 4 inputs signals through input terminals 1, 2.3 and forms a correction signal C consisting of color difference signals and a luminance signal S, and a high-frequency component of the correction signal C (hereinafter referred to as a correction contour signal d). ), a gain control circuit 6 that changes the gain of this corrected contour signal d, and a noise slice circuit 7 that removes minute noise from the output signal of the gain control circuit 6.

It is comprised of an adder 8 that adds the output signal of the noise slice circuit 7 and the luminance signal S, and outputs the output signal e to the a terminal 9.

The operation of the conventional high chroma image frequency corrector configured as described above will be explained with reference to FIGS. 4 to 8.

FIG. 4 shows an example of the internal configuration of the multi-IJ hook circuit 4 shown in FIG. 3. 10 is a luminance signal matrix circuit that forms the luminance signal Y; 11, 12, 13.17 is an adder; 14
, I5, 16 are negative clip circuits that set the negative signal to "0", and the correction signal C is <RY>+<G-Y>+<B-Y, which is the sum of the negatively clipped color difference signals. > (“KU” is a signal in which the negative value is “0”) is output.

FIG. 5 shows an example of the internal configuration of the high-pass filter 5 shown in FIG. 3. 18 is a t time delay circuit, 19 is a coefficient unit that multiplies the value of the number in the circle, and 20 is an adder. Here, when the correction signal C shown in FIG. 6 is input to this high-pass filter 5,
A corrected contour signal d of high frequency components as shown in FIG. 6 is obtained. The frequency characteristics of this noise filter 5 are as shown in FIG.

FIG. 8 shows signal waveforms at various parts in FIG. 3. Now, as shown in Fig. 8, when the R (red) signal a and the luminance signal change, the color changes from black to R (red) to black to R (red) to white to R (red). (At this time, G (green) and B (blue) are set to 0 degrees outside the white breath, so the correction signal becomes the color difference signal RY.) Then, the correction signal C becomes the color difference signal RY as described above. The corrected contour signal d obtained from the correction signal C by the high-pass filter 5 changes as shown in FIG. 8 as described above, and the corrected contour signal d and the luminance signal S are added. As shown in FIG. 8, a frequency-corrected luminance signal (adder output signal) e is obtained in a high chroma image.

Problems to be Solved by the Invention However, the high chroma image frequency corrector configured as described above corrects the contour when the brightness signal change and the correction signal change are in phase, but when the brightness signal change and the correction signal change are in opposite phase. On the other hand, there was a problem that the outline was blurred. That is, as shown in FIG. 8, when the brightness signal change and the correction signal change are in phase, for example, when the color changes from black to R (red) to black, the contour is corrected, but the brightness signal change and the correction signal change. When the change is in the opposite phase, for example, the color changes from R (red) to white to R (
When the color changes to red), the outline becomes blurred.

The above problems cannot be avoided.

The present invention solves the above problem, and aims to provide a high chroma image frequency corrector that always corrects the outline of a high chroma image, regardless of whether the brightness signal changes and the correction signal changes, or whether they are in-phase or out-of-phase. be.

Means for Solving the Problems In order to solve the above problems, the high chroma image frequency corrector of the present invention includes a matrix circuit which inputs an R-G-B signal and forms a correction signal consisting of a chromaticity signal and a luminance signal. , a first high-pass filter that extracts a high-frequency component of the correction signal, a second high-pass filter that extracts a high-frequency component of the luminance signal, and a positive/negative polarity of the output signals of the first and second high-pass filters. a polarity comparison circuit that compares polarities; a polarity inversion circuit that inverts the polarity of the output signal of the first high-pass filter; inputting the output signal of the first high-pass filter and the output signal of the polarity inversion circuit; The device includes a selection circuit that selects and switches one of the signals based on the output signal of the polarity comparison circuit and outputs the selected signal, and an adder that adds the output signal of the selection circuit and the luminance signal.

Effect: With the above configuration, the first high-pass filter extracts a corrected contour signal, which is a high-frequency component of a correction signal, and the second high-pass filter extracts a brightness contour signal, which is a high-frequency component of a luminance signal. Here, the polarity of the corrected contour signal and the brightness contour signal are compared by a polarity comparison circuit, and based on the output signal of this polarity comparison circuit, a selection circuit selects the corrected contour signal itself if the polarity is the same, and selects the correction contour signal itself if the polarity is the same. In this case, a signal obtained by inverting the corrected contour signal using a polarity inverting circuit is selected. Therefore, by adding the output signal of this selection circuit and the luminance signal, the frequency of the high chroma image is always corrected, regardless of whether the luminance signal change and the correction signal change are in phase or out of phase.

EXAMPLE Hereinafter, an example of the present invention will be described based on the drawings. It should be noted that the same components as those of the conventional example shown in FIG.

FIG. 1 is a block diagram of a high chroma image frequency corrector showing an embodiment of the present invention.

The high chroma image frequency corrector of the present invention newly inputs the luminance signal S from the matrix circuit 4 to the conventional configuration shown in FIG. a second high-pass filter 21 that extracts
, a polarity comparison circuit 22 that compares the polarity of the corrected contour signal C and the brightness contour signal i, and a polarity inversion circuit 2 that inverts the polarity of the output signal (corrected contour signal) of the noise slice circuit 7.
3 and a selection circuit 24 which selects and outputs the corrected contour signal which is the output signal of the noise slice circuit 7 and the output signal g of the polarity inversion circuit 23 based on the output signal f of the polarity comparison circuit 22. It is composed of

Note that the adder 8 adds the luminance signal and the output signal of the selection circuit 24.

The second high-pass filter 21 differs from the high-pass filter 5 only in the input signal, but its operation, characteristics, etc. are similar.

The operation of the high chroma image frequency corrector configured as described above will be explained using the main waveform diagram of FIG. 2.

Figure 2 is similar to Figure 8, with colors ranging from black to R (red) to black to R.
(red) to white to R (red).

As can be seen from FIG. 2, the output signal f of the polarity comparison circuit 22 is at a low level when the polarities of the corrected contour signal d and the brightness contour signal i are in the same phase, and is at a high level when the polarities are opposite to each other. When this output signal f is low level, the corrected contour signal d is selected, and when it is no level, the output signal g of the polarity inverting circuit 23 is selected and output, so that the output signal of the selection circuit 24 is By adding the luminance signal e and the luminance signal e in the adder 8, a luminance signal (adder output signal) e whose high frequency components are corrected is obtained as shown in FIG.

In this way, the corrected contour signal d, which is the high frequency component of the corrected signal C,
A polarity comparison circuit 22 compares the polarities of the brightness contour signal, which is a high-frequency component of the brightness signal for polarity discrimination, with the polarity comparison circuit 22, and based on the output signal f, if the polarities are the same, the corrected contour signal d is directly used.
In the case of reverse polarity, the selection circuit 24 selects and outputs the inverted signal g of the correction contour signal obtained from the polarity inversion circuit 23, so that the luminance signal change and the correction signal change are in phase or in opposite phase. Regardless, you can always perform frequency correction for high-chroma images.

In this embodiment, the correction signal is obtained from the R-Y, G-Y, and B-Y color difference signals as in the conventional example, but other signals equivalent to these, such as I and Q Needless to say, it's good for traffic lights, etc.

Effects of the Invention As described above, according to the present invention, the polarities of the high-frequency component of the correction signal (corrected contour signal) and the high-frequency component of the luminance signal are compared, and the corrected contour signal or the corrected contour is determined according to the polarity. By selecting the inverted signal of the signal and adding it to the brightness signal, it is possible to always perform frequency correction of a high chroma image, regardless of whether the change in the correction signal and the change in the brightness signal are in phase or out of phase.

Therefore, it is possible to eliminate the development in which the outline is blurred, which occurs when the change in the correction signal and the change in the luminance signal are in opposite phases, as in the conventional case, and it is possible to always emphasize the outline of a high-chroma image.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a high chroma image frequency corrector showing an embodiment of the present invention, FIG. 2 is a signal waveform diagram of each part of FIG. 1,
Figure 3 is a block diagram of a conventional high-chroma image frequency corrector.
4 is a circuit diagram showing an example of the internal configuration of the matrix circuit 4 shown in FIG. 3, and FIG. 5 is a circuit diagram showing an example of the internal configuration of the matrix circuit 4 shown in FIG.
6 is a waveform diagram for explaining the operation of the high-pass filter 5 in FIG. 3. FIG. 7 is a characteristic diagram showing the frequency characteristics of the high-pass filter 5 in FIG. 3. The figure is a signal waveform diagram of each part in FIG. 3. I, 2.3... Input terminal, 4... Matrix circuit, 5... (First) high pass filter, 6... Gain control circuit, 7... Noise slice circuit, 8
...Adder, 9...Output terminal, 21...Second high-pass filter, 22...Polarity comparison circuit, 23...
Polarity inversion circuit, 24... Selection circuit, a... R (red) signal, b... Luminance signal, C... Correction signal, d...
・Corrected contour signal, e...Adder output signal (frequency-corrected luminance signal), f...Polarity comparison circuit output signal,
g: polarity inversion circuit output signal, h: selection circuit output signal, i: luminance contour signal.

Claims (1)

[Claims] 1. A matrix circuit that inputs R, G, and B signals and forms a correction signal consisting of a chromaticity signal and a luminance signal, and a first high-pass filter that extracts a high frequency component of the correction signal.
a second high-pass filter that extracts a high-frequency component of the luminance signal; a polarity comparison circuit that compares the positive and negative polarities of output signals of the first and second high-pass filters; and an output signal of the first high-pass filter. a polarity inverting circuit that inverts the polarity of the polarity, the output signal of the first high-pass filter and the output signal of the polarity inversion circuit are input, and one of the signals is selected and switched according to the output signal of the polarity comparison circuit and output. A high chroma image frequency corrector comprising: a selection circuit; and an adder that adds the output signal of the selection circuit and the luminance signal.