JPH0832057B2 - High saturation image frequency corrector - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-saturation image frequency corrector for improving the sharpness of a particularly saturated image obtained from a television signal or the like.

2. Description of the Related Art As a conventional high-saturation image frequency corrector, there is a method of adding each color difference signal and adding its contour signal component to a luminance signal (for example, Haruo Sakata, "Resolution of color television high-saturation image", television Journal VOL 34, NO2,198
0).

A conventional high saturation image frequency corrector will be described with reference to the block diagram of FIG.

The conventional high-saturation image frequency corrector inputs the R (red) signal a, G (green) signal, and B (blue) signal processed by the process circuit via the input terminals 1, 2, and 3, respectively, and outputs the color difference signal. A matrix circuit 4 for forming a correction signal c and a luminance signal b, and a high-pass filter 5 for extracting a high frequency component of the correction signal c (hereinafter referred to as a corrected contour signal d).
A gain control circuit 6 that changes the gain of the corrected contour signal d, a noise slice circuit 7 that removes minute noise in the output signal of the gain control circuit 6, and an output signal of the noise slice circuit 7 and the luminance signal b are added. Then
The adder 8 outputs the output signal e to the output terminal 9.

The operation of the conventional high-saturation image frequency corrector configured as described above will be described with reference to FIGS.

FIG. 4 shows an example of the internal configuration of the matrix circuit 4 of FIG. Reference numeral 10 is a luminance signal matrix circuit that forms the luminance signal Y, 11, 12, 13, 17 are adders, and 14, 15, 16 are negative clipping circuits that set the negative signal to "0", and as the correction signal c, <R-Y> + <G-Y> + <B-Y>("<>" is a signal in which the negative is "0"), which is obtained by adding the negatively clipped color difference signals, is output.

FIG. 5 shows an example of the internal configuration of the high-pass filter 5 shown in FIG. Reference numeral 18 is a t-time delay circuit, 19 is a coefficient unit for multiplying the value in the circle, and 20 is an adder. When the correction signal c shown in FIG.
The corrected contour signal d of the high frequency component as shown in the figure is obtained.
The frequency characteristic of the high pass filter 5 is as shown in FIG.

FIG. 8 shows the signal waveform of each part in FIG. Now, as shown in FIG. 8, when the R (red) signal a and the brightness signal b change, that is, the color is black to R (red) to black to R (red) to.
Consider a case where the color changes from white to R (red) (at this time, G (green) and B (blue) are set to "0" except for white, so that the correction signal becomes the color difference signal RY). Then, the correction signal c is output as shown in FIG. 8 as described above, and the correction contour signal d obtained from the high pass filter 5 from the correction signal c changes as shown in FIG. The contour signal d and the brightness signal b are added to obtain a frequency-corrected brightness signal (adder output signal) e in the high saturation image as shown in FIG.

However, in the high-saturation image frequency compensator having the above-described configuration, the contour is corrected when the luminance signal change and the correction signal change are in the same phase, but when the luminance signal change and the correction signal change are in the opposite phase. On the contrary, there was a problem that the outline was blurred. That is, as shown in FIG. 8, when the luminance 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 luminance signal change and the correction signal are changed. When the change is in the opposite phase, for example, the color is R (red) to white to R
When it changes to (red), the outline is blurred.

 The above problems are inevitable.

The present invention solves the above problem, and an object of the present invention is to provide a high-saturation image frequency corrector that constantly corrects the contour of a high-saturation image regardless of whether the change in the luminance signal and the change in the correction signal are in-phase and anti-phase. is there.

Means for Solving the Problems In order to solve the above problems, a high-saturation image frequency corrector according to the present invention includes a matrix circuit for inputting R, G, B signals and forming a correction signal composed of a chromaticity signal and a luminance signal. , A first high-pass filter for extracting a high-frequency component of the correction signal, a second high-pass filter for extracting a high-frequency component of the luminance signal, and a positive or negative output signal of the first and second high-pass filters. A polarity comparison circuit for comparing polarities, a polarity inversion circuit for inverting the polarity of the output signal of the first high pass filter, an output signal of the first high pass filter and an output signal of the polarity inversion circuit are input, and The present invention is provided with a selection circuit that selects and switches one of the signals according to 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.

Operation With the above configuration, the first high-pass filter extracts the corrected contour signal which is the high-frequency component of the correction signal, and the second high-pass filter extracts the luminance contour signal which is the high-frequency component of the luminance signal. Here, the polarities of the corrected contour signal and the luminance contour signal are compared by a polarity comparison circuit, and the output signal of this polarity comparison circuit selects the corrected contour signal itself in the case of the same polarity, and the polarity of the opposite polarity signal is selected. In this case, a signal obtained by inverting the corrected contour signal by the polarity inverting circuit is selected. Therefore,
By adding the output signal of the selection circuit and the luminance signal, the frequency of the high-saturation image is always corrected regardless of whether the luminance signal change and the correction signal change are in-phase and anti-phase.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.
The same components as those shown in FIG. 3 of the conventional example are designated by the same reference numerals and the description thereof will be omitted.

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

The high-saturation image frequency corrector of the present invention newly inputs the luminance signal b from the matrix circuit 4 to the configuration of FIG. 3 of the conventional example, and the high-frequency component of the luminance signal for polarity determination (hereinafter referred to as the luminance contour signal i). Second high-pass filter 21 for extracting
, A polarity comparison circuit 22 for comparing the polarities of the corrected contour signal c and the luminance contour signal i, and a polarity inverting circuit 23 for inverting the polarity of the output signal (corrected contour signal) of the noise slice circuit 7.
And the output signal f of the polarity comparison circuit 22 selects 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, and adds a selection circuit 24 for switching and outputting. It is configured. The adder 8 adds the luminance signal b and the output signal h of the selection circuit 24.

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

The operation of the high-saturation image frequency corrector configured as described above will be described with reference to the waveform chart of the main part of FIG.

Similar to FIG. 8, in FIG. 2, the color is black-R (red) -black-
It shows a case where the state changes from 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 low level when the polarities of the corrected contour signal d and the luminance contour signal i are in phase, and is high level when they are in opposite phase, and the selection circuit 24 is When the output signal f is low level, the corrected contour signal d is selected, and when it is high level, the polarity reversing circuit 23.
Since the output signal g of the above is selected and switched and output, the output signal h of the selection circuit 24 and the luminance signal b are added by the adder 8 to obtain the luminance in which the high frequency component is corrected as shown in FIG. A signal (adder output signal) e is obtained.

As described above, the polarity of the corrected contour signal d, which is the high frequency component of the correction signal c, and the polarity of the luminance contour signal, which is the high frequency component of the luminance signal for polarity determination, are compared by the polarity comparison circuit 22, , If they have the same polarity, the corrected contour signal d
In the case of the opposite polarity, the inversion signal g of the corrected contour signal obtained from the polarity inversion circuit 23 is selected by the selection circuit 24 and is output by switching, so that the luminance signal change and the correction signal change are in phase and in phase. Regardless, it is possible to always correct the frequency of a high saturation image.

Incidentally, in the case of the present embodiment, the correction signal is obtained from the color difference signals of RY, GY, and BY in the same manner as in the conventional example, but other signals equivalent to these, such as I and Q, are used. It goes without saying that signals are good.

As described above, according to the present invention, the polarities of the high frequency component (correction contour signal) of the correction signal and the high frequency component of the luminance signal are compared, and the correction contour signal or the correction contour signal of the correction contour signal is compared according to this polarity. By selecting the inverted signal and adding it to the bright year signal, it is possible to always perform the frequency correction of the high-saturation image regardless of whether the change of the correction signal and the change of the luminance signal are in-phase or anti-phase. Therefore, it is possible to eliminate the conventional development that blurs the contour that occurs when the change in the correction signal and the change in the luminance signal are in opposite phases, and it is possible to always emphasize the contour of the high-saturation image.

[Brief description of drawings]

FIG. 1 is a block diagram of a high-saturation image frequency corrector showing an embodiment of the present invention, FIG. 2 is a signal waveform diagram of each part of FIG. 1,
FIG. 3 is a block diagram of a conventional high saturation image frequency corrector,
FIG. 4 is a circuit diagram showing an example of the internal configuration of the matrix circuit 4 of FIG. 3, and FIG. 5 is a high pass filter 5 of FIG.
6 is a circuit diagram showing an example of the internal configuration of FIG. 6, 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 frequency characteristics of the high-pass filter 5 in FIG. The figure is a signal waveform diagram of each part of FIG. 1,2,3 …… Input terminals, 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 reversal circuit, 24 ... selection circuit,
a ... R (red) signal, b ... luminance signal, c ... correction signal, d ... correction 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 for inputting R, G, B signals and forming a correction signal composed of a chromaticity signal and a luminance signal,
A first high-pass filter for extracting high-frequency components of the correction signal, a second high-pass filter for extracting high-frequency components of the luminance signal, and positive and negative polarities of output signals of the first and second high-pass filters. And a polarity inversion circuit that inverts the polarity of the output signal of the first high-pass filter, an output signal of the first high-pass filter and an output signal of the polarity inversion circuit, and the polarity A high-saturation image frequency corrector comprising: a selection circuit that selects and switches one of the signals according to the output signal of the comparison circuit and outputs the selected signal; and an adder that adds the output signal of the selection circuit and the luminance signal. .