JPH07114360A - Method for processing display video and device therefor - Google Patents

Abstract

PURPOSE:To reduce pseudo contour of a video to be displayed on a display panel having a small number of gradations. CONSTITUTION:An input video signal is input to a Y/C separation and color demodulation part 1, or input signals R, G and B are input to a reverse matrix part 5 and converted into Y, R-Y and B-Y signals, the digital data of the Y signal in the Y, R-Y, B-Y signals is input to a pseudo outline reducing part 10 via A/D converting parts 2, 3, 4, 6, 7 and 8, correlations of horizontal and vertical directions between pixels of a display video are detected, average value data between the pixels is calculated for parts where the correlations are large, the Y signal of the average value data is gained and on the other hand, the digital data of the R-Y and B-Y signals are input to data adjusting parts 11 and 12, their phases are adjusted with that of the Y signal, input to a matrix part 13 and converted into R, G and B signals to be displayed on a panel having a small number of display gradations such as PDP and the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to digital video signal processing and image display technology in a display system such as a television, and more particularly to a display panel (eg PDP; Plas).
The present invention relates to a display image processing method and apparatus for reducing a pseudo contour (pseudo contour) of an image displayed on a ma Display Panel.

[0002]

2. Description of the Related Art This type of PDP is excellent in a large screen among flat displays and is capable of full-color display and high-speed gradation display, so that it is a thin large-screen color display device (for example, a wall-mounted television). ) Is about to be used.

However, the conventional PDP display panel has a small number of display gradations (R, G, and B are each 6 bits (64 bits).
Gradation)), the brightness of the display image changes smoothly, for example, in the area of the picture, there is a conspicuous difference in brightness, and as shown in FIG. A pseudo contour is generated, and the pseudo contour is also generated in the shadow (shown by b in the same figure).

By the way, when a normal television signal (NTSC signal) or a signal corresponding thereto (a signal such as LD or VTR) is sampled and can be displayed on the display panel, that is, when digital signal processing is performed, the display floor of the display panel is displayed. If the number of tones is at least 8 bits (256 gradations), the above-described luminance step and pseudo contour of the display image are not noticeable.

[0005]

Therefore, when a display panel having a display gradation number of 8 bits (256 gradations) is used, there is no lack of resolution, and there is no noticeable level difference or pseudo contour in the displayed image. Therefore, a good display image can be obtained.

However, the current PDP has a display gradation number of about 6 bits (64 gradations), and there is a drawback that a step difference in brightness and a pseudo contour caused by insufficient resolution are conspicuous and the displayed image is bad. .

The present invention has been made in view of the above problems, and an object thereof is to reduce pseudo contours (false contours) of a display image on a display panel having a small number of display gradations and to improve image quality of the display image. It is an object of the present invention to provide a display image processing method and an apparatus thereof that can achieve the above.

[0008]

In order to achieve the above object, a method and apparatus for processing a display image according to the present invention include:
When an input video signal or input R, G, B signals are digitally processed in a predetermined manner and an image is displayed on a display panel having a predetermined number of display gradations, the correlation between each pixel of the displayed image is detected and the correlation is detected. For a portion where is large, the average value data between the same pixels is calculated, an image using the calculated average value data is displayed on the display panel, and the pseudo contour of the displayed image is reduced. To do.

[0009]

According to the above means, the input video signal or the input R, G, B signals are subjected to predetermined processing to Y, RY, B-.
After being converted into a Y signal and digitally converted, the Y signal is delayed by 1H and also delayed by 1 dot.

While the difference between the Y signal delayed by 1H and the current Y signal is calculated, the difference between the Y signal delayed by 1 dot and the current Y signal is calculated, and each pixel of the display image is calculated based on these differences. The amount of edge in the horizontal direction and the amount of edge in the vertical direction (correlation between the horizontal direction and the vertical direction) are detected.

The Y signal delayed by 1H and the current Y signal are added and right-shifted by 1 bit.
While the average value of the signals is calculated, the Y signal delayed by one dot and the current Y signal are added and right-shifted by 1 bit, whereby the average value of Y is calculated.

For a portion where the detected edge amount between pixels is small (for a portion where n correlation between pixels is large), the Y signal and RY, BY signal of the calculated average value can be displayed by matrix conversion. R, G, B.
Therefore, in the place where the horizontal and vertical edge amounts of the display image are small, the display image changes smoothly,
Although the pseudo contour is conspicuous, since the brightness of the Y signal is increased, the pseudo contour becomes inconspicuous.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A method and apparatus for processing a display image according to the present invention include a digital signal processing of an input video signal or an input R, G, B signal to a display panel (for example, a PDP having a small number of display gradations). When displaying, the horizontal and vertical correlations between each pixel of the display image are detected, that is, the horizontal and vertical edge amounts of the display image are detected, and the detected edge amount is medium or large. If the signal processing is the same as before, and if the detected edge amount is small (when the correlation between the pixels is large), average value data between pixels is calculated for the location where the correlation is large, and this calculation is performed. It is possible to display an image using average value data on the display panel.

Therefore, the display image processing apparatus of the present invention has the configuration shown in FIGS. 1 and 2. In FIG. 1, this processing device Y / C separates an input video signal into a luminance signal (Y signal) and a color signal (C signal), and performs color demodulation by the separated color signal (C signal) to obtain a color difference signal ( R-
Y / C separation and color demodulation unit 1 for converting to Y, BY signals)
And A / D converters 2 to 4 for digitally converting the separated and demodulated Y, RY, and BY signals, and Y, R- for inverse matrix conversion of the input R, G, and B signals.
Inverse matrix section 5 for obtaining Y, BY signals, A / D conversion sections 6-8 for digitally converting these Y, RY, BY signals, and A / D conversion sections 2-4. Or outputs of A / D conversion 6 to 8 Y, RY, B
-ROM or R for digital data of Y signal
A signal processing unit 9 that performs digital γ correction by a look-up table using AM (memory) and performs non-linear processing, etc.
And a pseudo-contour reducing unit 10 that detects a horizontal and vertical correlation between pixels for the Y signal, and adjusts based on the detected correlation to reduce a pseudo-contour (false contour) of a display image. Data adjusting units 11 and 12 for phase-matching the processed RY and BY signals with the Y signal.
And the pseudo contour reducing section 10 and the data adjusting sections 11 and 12
And a matrix section 13 for obtaining the primary color signals (R, G, B signals) by matrix-converting the Y, RY, and BY signals adjusted by.

The pseudo contour reducing section 10 adds a 1H delay line section 10a for delaying the digital data of the input Y signal by 1H line and a first addition for adding the Y signal delayed by 1H line to the currently input Y signal. Section 10b and the first subtraction section 10 for calculating the difference (vertical edge amount) between the Y signal delayed by 1H line and the currently input Y signal.
c, a 1-dot delay unit 10d that delays the digital data of the input Y signal by 1 dot (clock), and a second addition unit 10e that adds the Y signal delayed by 1 dot to the currently input Y signal, Difference between the Y signal delayed by one dot and the currently input Y signal (horizontal edge amount)
The second subtraction unit 10f and the first subtraction unit 10c
First absolute value calculation unit 10 for calculating the absolute value of the calculation result of
g, the second absolute value calculation unit 10h that calculates the absolute value of the calculation result of the second subtraction unit 10f, and the values calculated by the first and second absolute value calculation units 10g and 10h are compared, A magnitude discriminator 10i that outputs this comparison result value (a magnitude discriminant value of the correlation in the horizontal direction and the vertical direction), and a first D / D that sequentially latches and outputs the digital data of the input Y signal.
FF (D-type flip-flop; latch means) section 10j and second D-FF (D-type flip-flop; latch means) section 10k for right-shifting the data obtained by the first adding section 10b by 1 bit. And a third D-FF (D that shifts the data obtained by the second addition unit 10b right by 1 bit
Type flip-flop; latch means) section 10l,
There is provided a decoder section 10m for outputting selection signals of the first to third D / FF sections 10j, 10k, 10l in accordance with the output magnitude determination value of the magnitude determining section 10i.

Next, the operation of the display image processing apparatus having the above configuration and the operation of the processing method thereof will be described in detail. In addition,
Since the circuits other than the pseudo contour reducing unit 10 are already known, detailed description of the other circuits will be omitted.

First, an image (or color image) by the input video signal or an image by the input R, G, B signals is PD.
P display panel (display gradation number is less than 256 gradations)
The Y / C separation and color demodulation unit 1 separates the Y signal and the C signal of the input video signal, and demodulates the color difference signals R-Y and B-Y by the C signal. The separated, demodulated Y, RY, and BY signals are input to the A / D converters 2 to 4, and each of the A / D converters 2 to 4 is an analog of the Y, RY, and BY signals. The signal is sampled at a predetermined sampling frequency (for example, 143 MHz) and converted into a digital signal having a predetermined number of quantization bits (for example, 8 bits).

On the other hand, instead of the input video signal, the input R,
When there are G and B signals, the inverse matrix section 5 inversely matrix-converts the input R, G and B signals to obtain Y, RY,
Let it be a BY signal. The converted Y, RY, and BY signals are input to A / D conversion units 6 to 8, and the A / D conversion units 6 to 8 convert analog signals of Y, RY, and BY signals. Similar to each of the A / D converters 2 to 4, it is converted into a digital signal (for example, 8 bits).

The Y, RY and BY signals of the digitally converted data are input to the signal processing section 9,
The signal processing unit 9 performs necessary processing on the Y, RY, and BY signals, for example, digital gamma correction using a lookup table, and non-linear processing. Note that the non-linear processing may not be necessary.

The Y signal (8-bit digital data) processed by the signal processing unit 9 is input to the pseudo contour reducing unit 10,
The RY and BY signals are the data adjusting units 11 and 12, respectively.
To enter. The data adjusting units 11 and 12 perform phase matching to match the input RY and BY signals to the phase of the Y signal, respectively.

The pseudo contour reducing section 10 has the structure shown in FIG. 2, and inputs the Y signal to the 1H delay line section 10a and the 1 dot delay section 10d. Therefore, the 1H delay line section 10a delays the Y signal by 1H period, and the 1 dot delay section 10d delays the Y signal by 1 clock.

Further, the Y signal is input to the first adding section 10b and the first subtracting section 10c, and the first adding section 10b outputs 1
The Y signal delayed by the H period and the current Y signal are added, and right-shifted by 1 bit to output a Y signal of 1/2 data (average value data), and the first subtraction unit 10c outputs the 1H period. The difference between the delayed Y signal and the current Y signal is calculated. That is,
The correlation (vertical edge amount of the display image) between pixels in the vertical direction of the display image of the display panel is detected.

Further, the Y signal is input to the second adding section 10e and the second subtracting section 10f, and the second adding section 10e adds the Y signal delayed by one clock and the current Y signal,
Further, the Y signal of 1/2 data (average value data) is shifted by 1 bit to the right, and the second subtraction unit 10f calculates the difference between the Y signal delayed by one clock and the current Y signal. That is, the correlation between the horizontal pixels of the display image on the display panel (the horizontal edge amount of the display image) is detected.

The vertical edge amount calculated above is the first
Input to the absolute value calculation unit 10g of the first absolute value calculation unit 1
0 g calculates the absolute value of the edge amount. The calculated horizontal edge amount is input to the second absolute value calculating unit 10h, and the second absolute value calculating unit 10h calculates the absolute value of the edge amount.

The absolute values of the calculated vertical and horizontal edge amounts of the display image are input to the magnitude discriminating unit 10i,
The size determining unit 10i determines whether the vertical edge amount (vertical correlation) is large and the horizontal edge amount (horizontal correlation) is large. That is, the magnitude of the correlation between adjacent pixels in the vertical and horizontal directions is determined. This determination result is the first to the third D / FF.
The selection signals of the sections 10j, 10k, and 10l are input to the decoder section 10m that outputs the selection signals.

The first D / FF section 10j sequentially latches and outputs the current input Y signal, and the second D / FF section 1j
0k is Y of the average value data obtained by the first addition unit 10b
The signals are sequentially latched and output, and the third D / FF unit 10l
Sequentially latches and outputs the Y signal of the average value data obtained by the second adding unit 10e.

Therefore, when the vertical edge amount of the display image is small, that is, when the correlation between pixels in the vertical direction is large, the decoder unit 10m determines the second D / FF unit based on the determination result by the size determining unit 10i. A selection signal for selecting 10k is output. As a result, the pseudo contour reducing section 10 outputs the average value data (pixel data) of the Y signals sequentially latched to the second D / FF section 10k.

When the horizontal edge amount of the display image is small, that is, when the correlation between pixels in the horizontal direction is large, the decoder unit 10m controls the third D / FF unit 10l based on the determination result by the size determining unit 10i. Outputs a selection signal for selection. As a result, the pseudo contour reducing section 10 has the third D
The average value data (pixel data) of the Y signals sequentially latched is output to the FF unit 10l.

When the horizontal and vertical edge amounts of the display image are medium or large, that is, when the correlation between the horizontal and vertical pixels is medium or small, the decoder unit 10m determines the result of the determination by the size determining unit 10i. Based on the above, a selection signal for selecting the first D / FF unit 10j is output. As a result, the false contour reducing section 10 outputs the pixel data of the current input Y signal which is sequentially latched to the first D / FF section 10j.

The pixel data of the Y signal output from the false contour reducing section 10 is input to the matrix section 13 together with the output pixel data of the RY and BY signals of the data adjusting sections 11 and 12, and the matrix section 13 outputs Y. , RY, BY signals are matrix-converted into R, G, B signals.

The R, G, B signals thus obtained are input to a display panel control device such as a PDP having a small number of display gradations (for example, 64 gradations), and an image is displayed on the PDP. In addition, average value data is used for a portion of the display image where the horizontal and vertical edges are small, and for a portion where the luminance of the display image changes smoothly.

Therefore, in a display panel in which the number of display gradations of a display image is small, even if a pseudo contour (pseudo contour) occurs, a portion where the brightness of the display image changes smoothly is determined by the adjacent pixels in the horizontal and vertical directions. Since the brightness is averaged, that is, the brightness is increased, the pseudo contour of the display image becomes inconspicuous, that is, the pseudo contour is reduced.

The current input video signal or the R, G, B signals are used as they are at a portion where the difference in brightness of the display image is large, that is, at a portion where the horizontal and vertical edges of the display image are medium or large. This is because the pseudo contour becomes inconspicuous due to the brightness difference.

[0034]

As described above, according to the present invention, when the input video signal or the input R, G, B signals are processed in a predetermined manner and the image is displayed on the display panel (for example, PDP), the display image is displayed. Detecting the correlation between each pixel in the horizontal and vertical directions, that is, detecting the horizontal and vertical edge amounts of the display image, and if the detected edge amount is medium or large, the signal processing is the same until then, When the detected edge amount is small (when the correlation is large)
In addition, since the average value data between pixels is calculated for a portion having a large correlation and an image using the calculated average value data can be displayed on the display panel, a display panel (PDP) having a small display gradation number is displayed. It is possible to make the pseudo contour (false contour) of the display image in (3) inconspicuous, that is, to reduce the pseudo contour, and to improve the image quality of the display image.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of a display image processing apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic partial block diagram of the processing apparatus shown in FIG.

FIG. 3 is a diagram illustrating a pseudo contour (false contour) of a display image.

[Explanation of symbols]

1 Y / C separation and color demodulation section 2, 3, 4, 6, 7, 8 A / D conversion section 5 Inverse matrix section 9 Signal processing section 10 False contour reduction section 10a 1H delay line section 10b First addition section 10c 1st subtraction part 10d 1 dot delay part 10e 2nd addition part 10f 2nd subtraction part 10g 1st absolute value calculation part 10h 2nd absolute value calculation part 10i Large / small determination part 10j 1st DFF ( D-type flip-flop)
Part 10k Second DFF (D type flip-flop)
Part 10l Third DFF (D type flip-flop)
Section 10m decoder section 11 and 12 data adjustment section 13 matrix section

Claims (4)

[Claims] 1. Input video signal or input R, G, B
When a signal is digitally processed in a predetermined manner and an image is displayed on a display panel having a predetermined number of display gradations, the correlation between each pixel of the display image is detected, and the average between the pixels is detected at a place where the correlation is large. A method of processing a display image, wherein value data is calculated, an image using the calculated average value data is displayed on the display panel, and a pseudo contour of the display image is reduced. 2. An input video signal is subjected to color difference separation, and Y, RY, BY signals obtained by color demodulation are respectively digitally converted, or input R, G, B signals are subjected to inverse matrix conversion. Digital conversion is performed, the digitally converted data is processed in a predetermined manner, and the processed data is matrix-converted to obtain R, G, B signals.
A method of processing a display image capable of displaying the image by the G and B signals on a display panel having a display gradation number smaller than 256 gradations, wherein a horizontal direction between pixels of the display image by the digitally converted Y signal. And an edge amount in the vertical direction are detected, average value data between pixels is calculated for a portion where the detected edge amount is small, and an image using the calculated average value data is displayed on the display panel. A method of processing a display image, characterized in that a pseudo contour of the display image is reduced. 3. An input video signal is subjected to color difference separation, and Y, RY and BY signals obtained by color demodulation are respectively digitally converted, or input R, G and B signals are inversely matrix converted. Digital conversion is performed, the digitally converted data is processed in a predetermined manner, and the processed data is matrix-converted to obtain R, G, B signals.
A display image processing apparatus capable of displaying an image by G and B signals on a display panel having a display gradation number smaller than 256 gradations, wherein a horizontal direction between pixels of the display image by the digitally converted Y signal. And a means for detecting an edge amount in the vertical direction, and a means for calculating average value data between pixels for a portion where the detected edge amount is small, and Y signal and RY of the calculated average value data, A display image processing apparatus characterized in that a BY signal is matrix-converted into R, G, and B which can be displayed. 4. An input video signal is subjected to color difference separation, and color demodulated Y, RY and BY signals are obtained, and the Y and R signals are obtained.
-Y and BY signals are digitally converted respectively,
The input R, G, B signals are inverse matrix converted to Y, R-
Y, BY signals are obtained, the Y, RY, BY signals are digitally converted, and one of these digitally converted Y, RY, BY signals is processed in a predetermined manner, and the processing is performed. The converted data is subjected to matrix conversion to obtain R, G, B signals, and the display image processing capable of displaying the image by the obtained R, G, B signals on a display panel having a display gradation number smaller than 256 gradations. The apparatus is a 1H delay means for delaying the Y signal by one horizontal scanning line (hereinafter abbreviated as 1H), a 1 dot delay means for delaying the Y signal by 1 dot, and the 1H delayed Y signal. And a current Y signal and add 1-bit right shift, and a first subtraction for calculating the difference between the 1H delayed Y signal and the current Y signal to detect a vertical edge amount. Means and the Y signal delayed by one dot and the current Y signal Second adding means for adding and shifting to the right by one bit; second subtracting means for calculating the difference between the Y signal delayed by one dot and the current Y signal to detect the edge amount in the horizontal direction; A first absolute value calculating means for calculating the absolute value of the difference obtained by the first subtracting means; a second absolute value calculating means for calculating the absolute value of the difference obtained by the second subtracting means; The magnitude determination means for determining the magnitude of the absolute value of the difference obtained by the first and second absolute value calculation means, the first latch means for latching and outputting the current Y signal, and the first addition means A second latch means for latching and outputting the Y signal, a third latch means for latching and outputting the Y signal obtained by the second adding means, and a determination result by the magnitude determining means. Decoder means for outputting a selection signal for selecting the first to third latch means. , The Y signal latched and output by any one of the first to third latching means and the predetermined processed RY and BY signals can be matrix-converted and displayed on the display panel. A display image processing device characterized by R, G, B.