KR100420032B1 - A method for displaying pictures on plasma display panel and an apparatus thereof - Google Patents

Abstract

The present invention relates to an image display method of a plasma display panel and an apparatus thereof. The image display method of the plasma display panel includes a plurality of subfields having different specific gravity, wherein the images of the respective fields displayed on the plasma display panel correspond to a 50 Hz input video signal, wherein the subfields are further composed of two consecutive subfield groups. And a specific gravity value assigned to each subfield group is divided by different values, and a gray scale value is displayed by combining the specific gravity values of the subfields to display a gray scale. The original gray scale is generated based on the input video signal. First step; Determining a spreading filter value based on the input video signal; A third step of generating a final gray level by applying the diffusion filter value determined in the second step to the original gray level generated in the first step; A fourth step of generating grayscale data corresponding to the final grayscale generated in the third step, wherein the grayscale data is distributed over the two subfield groups; And a fifth step of displaying an image on the plasma display panel according to the grayscale data generated in the fourth step, and can reduce flicker and pseudo contours.

Description

Image display method of plasma display panel and apparatus therefor {A METHOD FOR DISPLAYING PICTURES ON PLASMA DISPLAY PANEL AND AN APPARATUS THEREOF}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display method of a plasma display panel and a device thereof, and particularly, to reduce flicker and pseudo contours generated when an image is input by inputting a 50 Hz PAL (Phase Alternating by Line) image signal. An image display method of a plasma display panel and a device therefor.

A plasma display panel is a type of display element that recovers image data input as an electric signal by arranging a plurality of discharge cells in a matrix shape and selectively emitting them.

In order to show performance as a color display element in such a plasma display panel, gray scale display should be possible. As a method of implementing the gray scale display, a gray scale implementation method of dividing one field into a plurality of subfields and controlling the time division is used.

On the other hand, flicker is closely related to human visual characteristics. Generally, the larger the screen or the lower the frequency, the better the flicker is perceived by the eye.

When the image of the PAL image signal is implemented in the plasma display panel, the two conditions are satisfied to generate a large amount of flicker.

Accordingly, when the plasma display panel is driven at a vertical frequency of 50 Hz using a minimum increment array or a minimum decrease array, which is a conventional subfield array used in the plasma display panel, a large amount of flicker occurs.

Since the screen size cannot be adjusted among the two conditions in which flicker occurs as described above, flicker can be reduced by using a method of adjusting the remaining frequencies.

As such, there is a Korean Patent Application Publication No. 2000-16955 as a conventional method for reducing the flicker by adjusting the frequency. In this patent, in order to reduce a large screen flicker generated when driving a plasma display panel by inputting a 50 Hz video signal, subfields in one field are divided into two groups G1 and G2, and the weight arrangement of the subfields in each group is similar or The subfield arrays other than the LSB subfield are set to have the same structure, and the luminance weight is similarly distributed to the two subfield groups. This method is very effective in reducing flicker, compared to the subfield arrangement such as the conventional minimum increasing arrangement or the minimum decreasing arrangement.

FIG. 1 is a diagram illustrating a conventional subfield arrangement, and FIG. 2 is a diagram illustrating a conventional subfield arrangement, and FIG. 2 shows on / off of each subfield in a gray scale generated when flicker is implemented. A diagram showing an example.

1 and 2, in order to express 109 gray levels, 53 gray levels are represented in the subfield group G1, and 56 gray levels are represented in the subfield group G2.

In this case, the subfields of group G1 are turned on from SF1 to SF5, and only the subfields of group G2 are of temperature SF3, 4, and 6. Therefore, in SF6, the upper subfield, all the turned-off numbers are 0 in the group G1 and all the turned-on numbers are 4 in the group G2, so the weight difference in the upper subfield, that is, the turned-on number is 4, Since the position of the central axis of light emission of each group G1 and G2 is different from each other, flicker may occur. Although only four lines are described here, when more than one line has the same gradation, for example, when all 640 lines have the same gradation on a 640 × 480 size screen, many flickers are detected because the number of turns is 640. do.

An image displayed on one screen is often the same gray level among adjacent pixels. Therefore, when images of the same gradation are displayed over several lines, flicker due to the difference of the subfield weights between the subfield groups G1 and G2 as described above may be generated to the extent that the human eye is perceived.

As described above, in the prior art, the gray scales are expressed by allocating the luminance weights to the groups G1 + G2, but the flicker is not reduced in all the gray levels of the video signal. In other words, when the highest weight of the subfield expressing the gray level assigned to the group G1 and the highest weight of the subfield expressing the gray level assigned to the group G2 are different from each other, the positions of the optical center axes are different in the two groups. There is a problem that flicker occurs because of losing.

Accordingly, an object of the present invention is to solve the above-described problems, and the image display method and apparatus of the plasma display panel which reduces the flicker and pseudo contour by diffusing the subfield using a diffusion filter using human visual characteristics. To provide.

1 is a diagram illustrating a conventional subfield arrangement.

FIG. 2 is a diagram illustrating an example of on / off of each subfield in a gray level in which flicker occurs when the gray level is implemented using a conventional subfield arrangement.

3 is a diagram schematically illustrating an image display method of a plasma display panel according to an exemplary embodiment of the present invention.

4A and 4B illustrate an example of the diffusion filter illustrated in FIG. 3, and FIG. 4A illustrates an even field diffusion filter and FIG. 4B illustrates an odd field diffusion filter.

5A and 5B are diagrams showing on / off states of respective subfields in grayscale data as a result of applying the diffusion filter of FIGS. 4A and 4B to the gray scale in which the flicker shown in FIG. 2 is generated. Is the on / off state of each subfield when the even field spreading filter is applied, and FIG. 5B is the on / off state of each subfield when the odd field spreading filter is applied.

6 is a block diagram of an image display apparatus of a plasma display panel according to an embodiment of the present invention.

FIG. 7 is a detailed block diagram of a subfield coding unit in the image display device of the plasma display panel of FIG. 6.

FIG. 8 is a diagram illustrating an application of a diffusion filter coefficient value differently according to gray levels in an image display apparatus of a plasma display panel according to an exemplary embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

10: even field diffusion filter 20: odd field diffusion filter

100: image signal processor 200: basic signal generator

300: gamma correction and error diffusion unit 400: subfield coding unit

500: addressing unit 600: plasma display panel

410: tone generation unit 420: lookup table

430: reference signal generation unit 440: diffusion filter application unit

In order to achieve the above object, an image display method of a plasma display panel according to a feature of the present invention,

A plurality of subfields having different specific gravity of an image of each field displayed on the plasma display panel in response to a 50 Hz input video signal, wherein the subfield is again composed of two consecutive subfield groups, and is assigned to each subfield group. In the image display method of the plasma display panel in which the specific gravity is divided by different values and the gray scale is displayed by combining the specific gravity values of these subfields.

A first step of generating an original gradation based on the input video signal; Determining a spreading filter value based on the input video signal; A third step of generating a final gray level by applying the diffusion filter value determined in the second step to the original gray level generated in the first step; A fourth step of generating grayscale data corresponding to the final grayscale generated in the third step, wherein the grayscale data is distributed over the two subfield groups; And a fifth step of displaying an image on the plasma display panel according to the grayscale data generated in the fourth step.

In the third step, the spread filter value is set differently according to the even field and the odd field of the input video signal.

The spreading filter value of the even field and the spreading field value of the odd field may be set to be compensated for each pixel.

Moreover, the image display apparatus of the plasma display panel which concerns on the characteristic of this invention,

A plurality of subfields having different specific gravity of an image of each field displayed on the plasma display panel in response to a 50 Hz input video signal, wherein the subfield is again composed of two consecutive subfield groups, and is assigned to each subfield group. In the image display apparatus of the plasma display panel which divides the specific gravity value into different values and displays the gray scale by combining the specific gravity values of these subfields,

A video signal processor for digitizing the input video signal to generate digital video data; The final gray scale is generated by applying a diffusion filter value determined based on the input video signal to the original gray scale generated based on the digital image data generated by the video signal processor, and the gray scale data corresponding to the final gray scale, wherein the gray scale data A subfield coding section for generating data distributed across the two subfield groups; And an address designator configured to control an image corresponding to grayscale data output from the subfield coding unit to be displayed on the plasma display panel.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a diagram schematically illustrating an image display method of a plasma display panel according to an exemplary embodiment of the present invention.

As shown in FIG. 3, the gray scale display method of the plasma display panel according to an exemplary embodiment of the present invention is a method of visually spreading a disturbance of generated gray scales, by applying a diffusion filter to original gray scale data determined by an external image signal. The final gradation data is generated.

Here, when the spreading filter is applied to the original grayscale data, the even field spreading filter 10 is applied to the grayscale data of the even field, and the odd field spreading filter 20 is applied to the grayscale data of the odd field.

At this time, it is preferable that the gray level data conversion by the even field diffusion filter 10 and the gray level data conversion by the odd field diffusion filter 20 can be signal processed in the opposite direction to any pixel.

For example, if the even field spreading filter 10 adds an arbitrary filter value n to the gradation data of an even field and converts the gradation data for an arbitrary pixel, the odd field spreading filter 20 performs this even field spread. In order to correct the signal processing of the filter 10, the arbitrary filter value n is subtracted from the grayscale data of the odd field of the arbitrary pixel to convert the grayscale data.

4A and 4B show an example of the diffusion filter shown in FIG. 3, FIG. 4A shows an even field diffusion filter 10, and FIG. 4B shows an odd field diffusion filter 20.

As shown in Figs. 4A and 4B, the even field spreading filter 10 and the odd field spreading filter 20 are adapted to convert the original grayscale data by adding one of 0, + k, and -k to the original grayscale data. have.

In addition, the value and the odd number of the even field diffusion filter 10 for any pixel may be compensated for each pixel so that the grayscale data converted by the even field diffusion filter 10 and the odd field diffusion filter 20 may be compensated for each other. The sum of the values of the field diffusion filter 20 is configured to be zero.

In the embodiment of the present invention, the values of the respective diffusion filters 10 and 20 have one of 0, + k, and -k values, but for ease of explanation, it is assumed that k = 1. That is, the description will be made so that the values of the respective diffusion filters 10 and 20 have one of 0, +1, and -1.

5A and 5B show an on / off state of each subfield in grayscale data as a result of applying the diffusion filters 10 and 20 of FIGS. 4A and 4B to the grayscale data generated with the flicker shown in FIG. 2. 5A shows an on / off state of each subfield when the even field spreading filter 10 is applied, and FIG. 5B shows an on / off state of each subfield when the odd field spreading filter 10 is applied. to be.

As shown in Figs. 5A and 5B, as a result of converting the original grayscale data using the even field spreading filter 10 and the odd field spreading filter 20, both the even field and the odd field are group G1 and group for the subfield SF6. It can be seen that the difference in the number of turns between G2 is 2, which is greatly reduced compared to the prior art, and as a result, the weight difference of the upper subfield is reduced. Therefore, flicker is reduced by the use of the diffusion filters 10 and 20 according to the embodiment of the present invention.

6 is a block diagram of an image display apparatus of a plasma display panel according to an embodiment of the present invention.

As shown in FIG. 6, an image display apparatus of a plasma display panel according to an exemplary embodiment of the present invention includes an image signal processor 100, a basic signal generator 200, a gamma correction and error diffusion unit 300, and subfield coding. The unit 400 and the addressing unit 500 is included.

The video signal processor 100 digitizes a 50Hz PAL video signal input from the outside to generate RGB data.

The basic signal generator 200 generates a basic signal for image signal processing. The basic signal includes a vertical synchronization signal Vsync as a reference for a field signal, a horizontal synchronization signal Hsync as a reference for each line, and a clock signal Clock as a reference for the entire signal processing.

The gamma correction and error diffusion unit 300 receives RGB data output from the image signal processing unit 100, corrects the gamma value according to the characteristics of the plasma display panel, and performs a diffusion process on the surrounding pixels and outputs the display error. .

The subfield coding unit 400 receives the RGB data output from the gamma correction and error diffusion unit 300 and the basic signal generated by the basic signal generator 200 and generates gray level data corresponding to each RGB pixel value. . In this case, the gray level corresponding to the RGB pixel value is converted by an even field diffusion filter and an odd field diffusion filter in the subfield coding unit 400 to determine a final gray level. The final gray level is used to determine the subfield coding unit 400. The lookup table 420 within is referenced to generate spread grayscale data.

The address designator 500 includes a frame memory (not shown) that stores the grayscale data output from the subfield coding unit 400, and controls the plasma display panel 600 by using the grayscale data stored in the frame memory. do.

FIG. 7 is a detailed block diagram of the subfield coding unit 400 in the image display apparatus of the plasma display panel of FIG. 6.

As illustrated in FIG. 7, the subfield coding unit 400 includes an original gray scale generator 410, a lookup table 420, a reference signal generator 430, and a spread filter applying unit 440.

The original gray scale generation unit 410 receives the RGB pixel values generated by the gamma correction and error diffusion unit 300 and generates a corresponding original gray scale.

The reference signal generator 430 receives a basic signal (Vsync, Hsync, Clock) generated by the basic signal generator 200 and generates a reference signal for applying a diffusion filter. An even field and an odd field are determined according to the reference signal, and an operation of selecting one of detailed values of the diffusion filter, that is, one of 0, + k, and -k values is performed.

The spread filter applying unit 440 generates a final gray scale by applying a spread filter value determined according to the state of the reference signal generated by the reference signal generator 430 to the original gray scale generated by the original gray scale generator 410. The grayscale data corresponding to the final grayscale is generated by referring to the lookup table 420 and then output to the address designator 500.

For example, when the original gray scale generated by the original gray scale generator 410 is 109, one filter value among the spread filter values of FIGS. 4A and 4B according to the state of the reference signal generated by the reference signal generator 430. Is selected and added to the original gradation. If the even field spreading filter of FIG. 4A is selected, and + k, which is the spread field value of the first column of the second line, is selected, 109 + k plus + k is determined as the final gray level. . In the case where k is 1, the final gray level is 110, and gray level data corresponding to the 110 is referenced in the lookup table 420 and generated.

Therefore, the address specifying unit 500 receives the grayscale data according to the final grayscale diffused by the diffusion filter, not the grayscale data according to the original grayscale, and controls the driving of the plasma display panel 600, resulting in an image having reduced flicker. Can be displayed.

Meanwhile, in the exemplary embodiment of the present invention, one of the spread filter values of 0, k, and -k is determined in the original grayscale data so as to convert the original grayscale, but without using 0 in the spread filter value, + k, Only -k may be selected and used as the diffusion filter value.

Further, the order applied to the diffusion filter values of 0, + k, and -k may also be applied in an order other than the order shown in Figs. 4A and 4B.

In addition, although the diffusion filter is applied to the telephone station of the plasma display panel, the technical scope of the present invention is not limited thereto, and the pixel of the area where flicker or pseudo contour generation is detected on the plasma display panel by a known method is detected. The diffusion filter may be applied only to. Such techniques will be readily understood by those skilled in the art when referring to the above-described embodiments of the present invention without detail.

On the other hand, in the above embodiment, it has been described assuming that k value, which is the coefficient of each diffusion filter, is 1, but different coefficient values can be applied to the k value for a predetermined input gray level.

As shown in FIG. 8, the gamma value varies depending on the gray level, and the gamma value decreases from the high gray region to the low gray region through the gamma curve, resulting in sensitivity to visual characteristics toward the low gray region. Able to know. Accordingly, it can be seen that applying the diffusion filter value differently according to the gradation level can prevent or reduce the distortion of the image according to the gradation level.

Diffusion filter coefficient k = <1 for gradation levels less than 100 for a total of 256 gradation levels, 1 <k = <2 for gradation levels above 100 and less than 200, and 2 <k = <3 for gradation levels above 200 Or k> 3. Thus, by using a diffusion filter value different according to the gradation level, that is, a diffusion filter value having a small coefficient in the low gradation region sensitive to the visual characteristics and the high gradation region less sensitive to the visual characteristics, the image according to the gradation level The distortion phenomenon is reduced.

Although the present invention has been described with reference to the most practical and preferred embodiments, the present invention is not limited to the above disclosed embodiments, but also includes various modifications and equivalents within the scope of the following claims.

According to the present invention, a subfield is divided by applying a spread filter value determined according to a state of a reference signal generated based on a basic signal generated by a 50 Hz PAL video signal to an original gray scale determined by the 50 Hz PAL video signal. Flicker and pseudo contours generated when the image is displayed by dividing into groups can be reduced.

Claims (15)

A plurality of subfields having different specific gravity of an image of each field displayed on the plasma display panel in response to a 50 Hz input video signal, wherein the subfield is again composed of two consecutive subfield groups, and is assigned to each subfield group. In the image display method of the plasma display panel in which the specific gravity is divided by different values and the gray scale is displayed by combining the specific gravity values of these subfields. A first step of generating an original gradation based on the input video signal; Determining a spreading filter value based on the input video signal; A third step of generating a final gray level by applying the diffusion filter value determined in the second step to the original gray level generated in the first step; A fourth step of generating grayscale data corresponding to the final grayscale generated in the third step, wherein the grayscale data is distributed over the two subfield groups; And A fifth step of displaying an image on the plasma display panel according to the grayscale data generated in the fourth step; An image display method of a plasma display panel comprising a. The method of claim 1, And in the third step, the spread filter value is set differently according to the even field and the odd field of the input image signal. The method of claim 2, And the diffusion filter value of the even field and the diffusion field value of the odd field are set to be compensated with respect to an arbitrary pixel. The method of claim 1, And in the third step, the final gray scale data is generated by adding a diffusion filter value to the original gray scale. The method of claim 1, And a sixth step of generating a basic signal based on the input video signal before the first step. In the second step, the spread filter value is determined according to the state of the basic signal generated in the sixth step. An image display method of a plasma display panel. The method of claim 5, The diffusion filter has a value of one of 0, + k, and -k (where k is a diffusion filter coefficient and is a positive integer), and the value is determined according to the state of the basic signal. How to display images on the panel. The method of claim 6, And said diffusion filter coefficient (k) has a different value in accordance with said original gradation. The method of claim 7, wherein And said diffusion filter coefficient (k) has a smaller value when said original gradation is a low gradation region than when it is a high gradation region. A plurality of subfields having different specific gravity of an image of each field displayed on the plasma display panel in response to a 50 Hz input video signal, wherein the subfield is again composed of two consecutive subfield groups, and is assigned to each subfield group. In the image display apparatus of the plasma display panel which divides the specific gravity value into different values and displays the gray scale by combining the specific gravity values of these subfields, A video signal processor for digitizing the input video signal to generate digital video data; The final gray scale is generated by applying a diffusion filter value determined based on the input video signal to the original gray scale generated based on the digital image data generated by the video signal processor, and the gray scale data corresponding to the final gray scale, wherein the gray scale data A subfield coding section for generating data distributed across the two subfield groups; And An address designator for controlling an image corresponding to grayscale data output from the subfield coding unit to be displayed on the plasma display panel An image display device of a plasma display panel comprising a. The method of claim 9, The subfield coding unit A lookup table in which gradation data corresponding to the gradation is preset; An original gradation generator for determining an original gradation corresponding to the digital image data generated by the image signal processor; And The final gray scale is generated by applying a spread filter value determined based on the digital image data generated by the image signal processor to the original gray scale generated by the original gray scale generator, and the gray scale data corresponding to the generated final gray scale. A spreading filter applying unit which generates and outputs to the address designation unit by referring to the lookup table An image display device of a plasma display panel comprising a. The method of claim 10, A basic signal generator for generating a basic signal for processing image signals based on the input image signal; The subfield coding unit determines the spread filter value based on a state of a basic signal generated by the basic signal generator. An image display device of a plasma display panel. The method of claim 11, The subfield coding unit And a reference signal generator for generating a reference signal for determining the diffusion filter value based on the basic signal generated by the basic signal generator. The method of claim 12, The diffusion filter has a value of one of 0, + k, and -k (where k is a diffusion filter coefficient and is a positive integer), and the value is determined according to the state of the basic signal. Panel image display device. The method of claim 13, And said diffusion filter coefficient (k) has a different value in accordance with said original gradation. The method of claim 14, And said diffusion filter coefficient (k) has a smaller value when the original gradation is a low gradation region than when the original gradation is a high gradation region.