KR100505989B1 - Method And Apparatus of Processing Video Data For Plasma Display Panel - Google Patents

Abstract

The present invention provides a method and apparatus for processing video data of a plasma display panel which can reduce error diffusion and dithering noise.

The video data processing method of the present invention is a video data processing method of a plasma display panel for reducing the number of bits of video data by an error diffusion method and a dithering method, wherein the input video data is limited within an upper dither mask pattern range. Diffusing; And dithering the limited error spread video data using a plurality of dither mask patterns divided by gray and frame.

Description

Method and apparatus for processing video data of plasma display panel {Method And Apparatus of Processing Video Data For Plasma Display Panel}

The present invention relates to a method and apparatus for processing digital video data, and more particularly, to a method and apparatus for processing video data of a plasma display panel capable of reducing contour noise.

Recently, a plasma display panel (PDP), which is easy to manufacture a large panel, has attracted attention as a flat panel display device. The PDP displays an image by adjusting the gas discharge period of each of the pixels according to the digital video data. As such a PDP, a PDP having three electrodes as shown in FIG. 1 and driven by an AC voltage is representative.

The discharge cell of the AC PDP shown in FIG. 1 includes sustain electrode pairs 12A and 12B formed on the upper substrate 10 and data electrodes 20 formed on the lower substrate 18.

Each of the sustain electrode pairs 12A and 12B has a double layer structure of a transparent electrode and a metal electrode. The sustain electrode pairs 12A and 12B mainly provide a scan electrode 12A mainly supplying a scan signal for address discharge and a sustain signal for sustain discharge, and a sustain signal alternately supplied to the scan electrode 12A. It is separated by the sustain electrode 12B. The data electrode 20 is formed to intersect with the sustain electrode pairs 12A and 12B to supply a data signal for address discharge.

An upper dielectric layer 14 and a passivation layer 16 are stacked on the upper substrate 10 on which the sustain electrode pairs 12A and 12B are formed, and a lower dielectric layer 22 is formed on the lower substrate 18 on which the data electrode 20 is formed. do. The upper dielectric layer 14 and the lower dielectric layer 22 accumulate charges generated by the discharge. The protective film 16 prevents damage to the upper dielectric layer 14 due to sputtering of plasma particles during discharge and increases the emission efficiency of secondary electrons. The dielectric layers 14 and 22 and the protective layer 16 may lower the driving voltage applied from the outside.

A partition wall 24 is formed on the lower substrate 18 on which the lower dielectric layer 22 is formed, and a phosphor layer 26 is formed on the lower dielectric layer 22 and the surfaces of the partition wall 24. The partition wall 24 separates the discharge space to prevent the ultraviolet rays generated by the gas discharge from leaking into the adjacent discharge space. The phosphor layer 26 emits red (hereinafter, R), green (hereinafter, G), or blue (hereinafter, B) visible light by emitting light by ultraviolet rays generated by gas discharge. The discharge space is filled with an inert gas for gas discharge.

This discharge cell is selected by address discharge by the data electrode 20 and the scan electrode 12A, and the selected discharge cell maintains the discharge by sustain discharge by the sustain electrode pairs 12A and 12B. The discharge cell emits the phosphor 26 by ultraviolet rays generated during the sustain discharge to emit R, G, or B visible light. In this case, the discharge cell adjusts the sustain discharge period, that is, the number of sustain discharges according to the video data, thereby implementing gray scale for displaying an image. A color of one pixel is realized by combining three discharge cells coated with R, G, and B phosphors 26, respectively.

As a method of driving such a PDP, an ADS (Address and Display Separation) driving method that is driven by being divided into an address period and a display period, that is, a sustain period is typical. As shown in FIG. 2, the ADS driving method divides one frame 1F into a plurality of subfields SF1 to SF8 corresponding to each bit of video data. Each of the subfields SF1 to SF8 again has a reset period RPD for initializing a radiation cell, an address period APD for selecting a discharge cell, and a sustain period SPD for maintaining the discharge of the selected discharge cell. Is divided into Here, the PDP implements the corresponding gradation by assigning different weights to the subfields SF1 to SF8 in the sustain period SPD and combining the sustain period SPD according to the video data.

As such, the PDP displays an image using a pulse width modulation method in which the sustain period SPD is proportional to the video data signal. In this case, the display period and the non-display period are distributed in various forms within each frame due to subfields that separate each frame according to each bit of video data. Accordingly, the PDP displays an image by integrating light emitted in each subfield period. In this case, contour noise occurs due to a mismatch between the direction of integration of light assumed by the PDP and the visual characteristics recognized by the human eye. And the contour noise increases when there is continuous gradation such as when the human skin is being displayed. For example, the contour noise increases when successively displaying gray scales, such as 127-128, 63-64, 31-32 gray scales, which differ greatly in emission pattern.

In order to reduce such contour noise, a method of optimizing the order of subfields by a driving method of a PDP, a method of dividing subfields corresponding to the most significant bit (MSB), an equalizing pulse method, and error diffusion ), Dithering, and the like have been proposed. Among them, an equalization pulse method, an error diffusion method, and a dithering method are typical.

The equalization pulse method compensates video data by increasing or decreasing video data generating contour noise using an equalization pulse. However, as contour noise is related to motion, it requires a motion estimator and has a large memory that can store multiple look-up tables as it requires different equalization pulses depending on the speed of motion. There is a disadvantage in that the complexity of the hardware is large.

The error diffusion method calculates quantization error data of digital video data using a Floyd-Steinberg error diffusion filter and spreads the calculated error data to adjacent pixels with different weights. However, the error diffusion method has a problem in that an error diffusion pattern due to the constant error diffusion coefficient is generated as the error diffusion coefficient (i.e., the weight) for the neighboring pixel is constantly set and repeated for each line and frame.

The dithering method is to add appropriate noise so that the contour noise is inconspicuous. For example, European Patent Application No. 00250099.9 and the like disclose a method of repeatedly using a three-dimensional dither pattern corresponding to a plurality of frames, a plurality of lines and a plurality of columns in a PDP. However, the conventional dithering method has a problem in that dithering noise, which reduces the quality of an image, occurs at a specific gray level. In addition, the conventional dithering method has a problem such as flicker in low gradation expression by repeatedly using a three-dimensional dither pattern without dividing the low gradation and the high gradation.

Accordingly, it is an object of the present invention to provide a method and apparatus for processing video data of a PDP that can reduce contour noise.

Another object of the present invention is to provide a video data processing method and apparatus of a PDP that can reduce error spreading and dithering noise.

It is still another object of the present invention to provide a method and apparatus for processing video data of a PDP that can reduce dithering noise of a specific gray level.

In order to achieve the above object, the video data processing method of the PDP according to the present invention, in the video data processing method of the plasma display panel for reducing the number of bits of the video data by the error diffusion method and dithering method, the input video data is higher Limiting error diffusion within a gray dither mask pattern range; And dithering the limited error spread video data using a plurality of dither mask patterns divided by gray and frame.

The input video data is inverse gamma corrected video data.

The limited error spreading step may include: generating a first carry signal by adding error diffusion coefficients calculated by applying different weights to lower bits of some of the input video data and data of an adjacent pixel; Generating a second carry signal by comparing the first carry signal with a dither value of a position corresponding to the input video data in the upper gray scale dither mask pattern; And adding the second carry signal to the remaining upper bits of the input video data to output the second carry signal.

The generating of the first carry signal may further include adding a random error spreading coefficient to the calculated error spreading coefficients.

The dither mask pattern of the higher gray level may be selected from dither mask patterns corresponding to higher gray levels than gray levels corresponding to some bits of the input video data in a plurality of dither mask patterns stored in advance.

The generating of the second carry signal may include generating the second carry signal by performing an AND operation on the first carry signal and the selected dither value.

The dithering may include selecting a dither mask pattern of a corresponding gray level among the plurality of dither mask patterns using lower bits of a part of the limited error spread video data; Selecting a dither value at a position corresponding to the limited error spread video data among the selected dither mask patterns; And adding the selected dither value to upper bits of a part of the limited error spread video data.

The selecting of the dither value includes counting a vertical synchronization signal, a horizontal synchronization signal, and a pixel clock signal input from an external source, and selecting a position corresponding to the limited error spread video data using the counted signal. Characterized in that it comprises a.

The selecting of the dither value may include selecting the dither mask pattern by toggling dither mask patterns of different gradations for each frame according to the signal counting the vertical synchronization signal.

The selecting of the dither value may include comparing the limited error spread video data with a preset reference value and reducing the number of frames to be toggled when it is smaller than the reference value.

A video data processing method of a PDP according to the present invention is a video data processing apparatus of a plasma display panel for reducing the number of bits of video data by an error diffusion method and a dithering method, wherein the input video data is within a dither mask pattern range of an upper gray scale. A limited error diffuser for diffusing the limited error in the; And a dithering unit dithering the limited error spread video data using a plurality of dither mask patterns divided by gray and frame.

The input video data may further include an inverse gamma correction unit for outputting by inverse gamma correction.

The limited error diffusion unit may include a dither mask selector for selecting a dither value at a position corresponding to the input video data in the upper gray scale dither mask pattern; Comparing the first carry signal generated by error diffusion of the input video data and the dither value, a second carry signal is generated, and the second carry signal is added to the input video data to output limited error spread video data. It is characterized by including an error diffusion filter for.

The dither mask selector is a dither mask pattern of the upper gray level, and among the dither mask patterns stored in the dithering unit, among the dither mask patterns corresponding to higher gray levels than a gray level corresponding to some bits of the input video data. It is characterized by selecting any one.

The error spreading filter generates a first carry signal by adding error spreading coefficients calculated by giving different weights to lower bits of some of the input video data and data of adjacent pixels, and generates the first carry signal and the first carry signal. The dither value is compared to generate a second carry signal, and the second carry signal is added to the remaining upper bits of the input video data and output.

The error diffusion filter may generate the second carry signal by performing an AND operation on the first carry signal and the selected dither value.

The limited error diffusion unit may further include a random error diffusion coefficient generator for generating a random error diffusion coefficient to be added to the calculated error diffusion coefficients.

The dithering unit stores the plurality of dither mask patterns and selects and outputs a dither value corresponding to the limited error diffused video data among the stored dither mask patterns; A mask controller for indicating a position where the dither mask table corresponds to the limited error spread video data; And an adder for adding and dividing the dither value to the limited error spread video data.

The dither mask table selects a dither mask pattern of a corresponding gray level among the plurality of dither mask patterns using lower bits of some of the limited error spread video data, and selects a dither mask pattern in response to an instruction of the mask controller. The dither value of the position corresponding to the limited error spread video data is selected and output.

The adder adds and outputs the selected dither value to upper bits of the remaining part of the limited error spread video data.

The mask control unit may count a vertical synchronizing signal, a horizontal synchronizing signal, and a pixel clock signal input from an external device, and indicate positions corresponding to the limited error spread video data using the counted signals.

The mask control unit instructs the dither mask table to select while dithering the dither mask patterns of the corresponding gradation, which are different for each frame, according to the signal counting the vertical synchronization signal.

The mask controller may compare the limited error spread video data with a preset reference value and reduce the number of frames to be toggled when the reference value is smaller than the reference value.

Other objects and advantages of the present invention in addition to the above object will become apparent from the description of the preferred embodiment of the present invention with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to FIGS. 3 to 11.

3 is a block diagram schematically illustrating a video data processing apparatus of a PDP according to an embodiment of the present invention. The video data processing apparatus of the PDP shown in FIG. 3 includes a gamma correction unit 30, an error diffusion and dithering unit 32, a subfield mapping unit 34, connected between an input line of the video data and the PDP 38, The data driver 36 is provided.

The gamma correction unit 30 receives digital video data gamma-corrected to suit the luminance characteristic of the cathode ray tube CRT from the outside, that is, pixel data to be supplied to each of the cells (sub pixels) constituting the PDP 38. . The gamma correction unit 30 performs inverse gamma correction on each of the input pixel data to make the luminance characteristic according to the pixel data linear. For example, the gamma correction unit 30 outputs inverse gamma correction pixel data corresponding to the input pixel data by using a look-up table LUT that is set so that luminance characteristics according to the pixel data follow a 2.2 gamma curve. In this case, each of the pixel data output from the gamma correction unit 30 includes an integer part and a fractional part. For example, when 8-bit pixel data is input, the gamma correction unit 30 outputs the 12-bit corrected pixel data having a 6-bit integer part and a 6-bit fractional part, or the 8-bit integer part and 8-bit fractional part. The pixel data corrected by 16 bits having the same is output.

The error diffusion and dithering unit 32 outputs pixel data having a reduced number of bits by correcting each of the pixel data from the gamma correction unit 30 by an error diffusion method and a dithering method using a dither mask pattern. In this case, the error diffusion and dithering unit 32 reduces the influence of error diffusion to the gradation range of the upper dither mask pattern to reduce error diffusion noise such as flicker and dither noise. Detailed description of the error diffusion and dithering unit 32 will be described later.

The subfield mapping unit 34 maps each pixel data from the error diffusion and dithering unit 32 to a preset subfield pattern and outputs the mapping.

The data driver 36 latches the input data which is separated bit by bit according to the subfield pattern in the subfield mapping unit 34, and then, when the horizontal line drives the latched data line by line, Supply to address electrode lines.

The PDP 38 includes an address electrode line and a pair of sustain electrode lines intersecting the address electrode line with the discharge space therebetween. Each cell having a discharge space corresponding to the subpixel is formed at each intersection of the address electrode line and the sustain electrode line pair. The PDP 38 is a cell to be turned on by an address discharge according to data supplied from the data driver 36 to the address electrode line whenever the scan electrode line of the pair of sustain electrode lines is driven in the address period of each subfield. Select them. The PDP 38 causes the selected cells to maintain a discharge in the sustain period of each subfield by driving a pair of sustain electrode lines. In this case, as the number of bits of the video data is reduced by the error diffusion and dithering unit 32, the number of subfields constituting one frame is reduced, thereby sufficiently securing the address period. This drive is possible.

FIG. 4 illustrates a detailed configuration of the error diffusion and dithering unit 32 shown in FIG. 3, and the error diffusion and dithering unit 32 includes a limited error diffusion unit 40 and a dithering unit 42. Equipped.

The limited error diffuser 40 calculates the error diffusion coefficients of adjacent pixels calculated by the video data and the error diffusion filter from the gamma correction unit 30 and error diffuses the number of bits of the pixel data to output them. In this case, the limited error diffusion unit 40 adds a random error diffusion (hereinafter referred to as R-ED) coefficient to the error diffusion calculation to prevent an error diffusion pattern from occurring due to a constant error diffusion coefficient. The limited error diffusion unit 40 limits the influence of the error diffusion to the dither mask pattern range of the upper gray level using the dither mask patterns used in the dithering unit 50.

To this end, the limited error diffusion unit 40 includes an error diffusion filter 42, an R-ED coefficient generator 44 and a dither mask selector 46 connected to the error diffusion filter 42 as shown in FIG. 5. do.

The error diffusion filter 42 includes error diffusion operators (not shown) for error diffusion, and a line memory (not shown) for storing some lower bits, for example, a fractional part, to be used for error diffusion among adjacent pixel data. ). Specifically, when it is assumed that pixel data of 16 bits (integer part 8 bits, fractional part 8 bits) is input from the gamma correction unit 30, the error diffusion filter 42 includes lower 8-bit data corresponding to the fractional part of the 16 bits. Is stored in the line memory for use in the error diffusion operation of adjacent pixels. The error diffusion filter 42 reads a fractional portion of adjacent pixel data stored in the line memory and calculates error diffusion coefficients by assigning different weights according to the positions of the pixels.

For example, when the error diffusion filter 42 performs an error diffusion operation on the current P5 pixel as shown in FIG. 6, the error diffusion filter 42 has a weight of 1/16 on the fractional part of the P1 pixel adjacent to the P5 pixel, and 5 on the fractional part of the P2 pixel. An error diffusion coefficient for each of the P1 to P4 pixels is calculated by giving the weight of / 16, the weight of 3/16 to the fractional part of the P3 pixel, and the weight of 7/16 to the fractional part of the P4.

In addition, the error diffusion filter 42 calculates the error diffusion coefficients of the adjacent pixels P1 to P4 calculated as described above and the R-ED coefficient R generated from the R-ED coefficient generator 44. P6) The first carry signal " 0 " or " 1 " is generated by adding with the fractional part (lower 8 bits) of the data.

Further, the error diffusion filter 42 limits the error diffusion effect within the range of the dither mask pattern of the upper gray level among the dither mask patterns used in the dithering unit 50. Specifically, the error diffusion filter 42 compares the initial carry signal (hereinafter referred to as a first carry signal) generated by the error diffusion method with respect to the current pixel data and the dither value D1 from the dither mask selector 46. Generates the last error spreading carry signal (hereinafter referred to as the second carry signal) " 0 " or " 1 " to be added to some of the upper bits of the current pixel data, for example, the integer part (upper 8 bits).

To this end, the dither mask selector 46 uses the bits of some of the current pixel data input to the error diffusion filter 42, for example, the lower 3 bits of the integer part, to store the dither mask pattern stored in the dithering unit 50. Among them, a dither mask pattern corresponding to a higher gray level than the lower 3 bits is selected. For example, when the lower 3 bits of the integer part of the currently input pixel data are "010", that is, when the gray level is 2/8 as shown in FIG. 7, the dither mask selector 46 is higher than the 2/8. The dither mask pattern corresponding to any one of the gradations 3/8 to 7/8, for example, 4/8, is selected. In this case, the dither mask selector 46 dither mask patterns of four frames (1F to 4F) corresponding to 4/8 gray scales among the plurality of dither mask patterns stored in the dithering unit 50 as shown in FIG. 8. Error diffusion filter by selecting a dither value D1 corresponding to a current pixel data position of a current frame using a vertical synchronization signal V, a horizontal synchronization signal H, and a pixel clock signal P input from an external device. Supply to (42).

Accordingly, the error diffusion filter 42 generates a second carry signal by comparing the dither value D1 from the dither mask selector 46 with the first carry signal generated by the error diffusion, and generates the second carry signal. The 8-bit pixel data is output by adding the signal to the integer part (upper 8 bits) of the current pixel data. Specifically, the error diffusion filter 42 has a second carry signal "1" when the first carry signal generated by the error diffusion is "1" and the dither value D1 from the dither mask selector 46 is "1". ", And otherwise generate the last carry signal" 0 ". In other words, the error diffusion filter 42 performs an AND operation on the first carry signal generated by the error diffusion and the dither value D1 from the dither mask selector 46 to generate a second carry signal. . Accordingly, the pixel position where the second carry signal “1” due to the error diffusion is added to the pixel data in the error diffusion filter 42 is higher than the lower 3 bits among the pixel data as indicated by the bold line in FIG. 7. It is limited to the position set to "1" in the gradation dither mask pattern. As a result, the influence of the error diffusion in the error diffusion filter 42 is limited to the range of the upper gradation dither mask pattern, thereby minimizing noise such as a flicker phenomenon due to error diffusion.

FIG. 9 illustrates a specific configuration of the dithering unit 50 shown in FIG. 4, wherein the dithering unit 50 is connected to an output line of the dither mask control unit 52 and the limited error diffusion unit 40. And an adder 56 connected to the dither mask table 54 and the output line of the limited error diffuser 40.

The dither mask table 54 stores different dither mask patterns for each gray level and for each frame. For example, as shown in FIG. 8, dither mask patterns having a cell size (subpixel) of 4 × 4 are separated by eight gray levels, such as 0 to 7/8, corresponding to the lower 3 bits of the pixel data. As each of the dither mask patterns is separated into four frames 1F to 4F, the dither mask table 54 stores a total of 32 dither mask patterns. Referring to FIG. 8, dither value " 1 in each of the dither mask patterns of 0, 1/8, 2/8, 3/8, 4/8, 5/8, 6/8, 7/8, 7/8 gradation It can be seen that the number of cells set to "" increases in the order of zero, two, four, six, eight, ten, twelve, and fourteen. The positions of the cells set to the dither value "1" for each of the four frames 1F to 4F are different from each other. The position of "1" in each of these dither mask patterns may vary in accordance with the designer's needs. According to the dither mask pattern, the position of the on cell corresponding to the dither value "1" can be controlled spatially and temporally. In addition, as the position of the dither value "1" in the dither mask patterns is different for each gray level and for each frame, dither noise such as lattice noise due to repetition of a constant dither mask pattern may be reduced.

The dither mask table 54 storing such dither mask patterns inputs lower bits of a part of the pixel data input from the limited error diffusion unit 40, for example, 3 bits of 8-bit pixel data. The dither mask table 54 selects a dither mask pattern having a gray level corresponding to the input lower 3 bits from among the dither mask patterns shown in FIG. 8. Subsequently, the dither mask table 54 selects the dither value D2 corresponding to the frame and cell position indicated by the mask controller 52 among the dither mask patterns of the selected gray level and outputs the dither value D2 to the adder 56.

To this end, the dither mask controller 52 counts the vertical synchronizing signal V input from an external controller (not shown) and indicates a corresponding frame among the four frames 1F to 4F, and the horizontal synchronizing signal H Each pixel clock signal P is counted to indicate a horizontal line and a vertical line, that is, a cell position in the corresponding frame. In this case, the dither mask controller 52 uses the signal of counting the vertical synchronizing signal V, and the dither mask table 54 toggles the first to fourth frames 1F to F4 while the dither mask pattern of the corresponding gray level is used. Allows you to select

In addition, the dither mask controller 52 controls the number of frames toggled in the dither mask table 54 according to the gradation of the input pixel data. In detail, the dither mask controller 52 determines whether the input pixel data is low gray data or high gray data by inputting pixel data from the limited error diffusion unit 40 and comparing the pixel data with a preset reference value. Here, when the input pixel data is determined to be high gradation data, the dither mask controller 52 selects a dither mask pattern while the dither mask table 54 toggles three frames or four frames 1F to 4F as described above. Let's do it. When the input pixel data is determined to be low gradation data, the dither mask control unit 52 causes the dither mask table 54 to select two dither mask patterns while toggling two frames among the four frames 1F to 4F. Accordingly, when low gray pixel data is continuously displayed for a plurality of frames, flicker due to a dither mask pattern different for each frame may be prevented.

The adder 56 corrects by adding a dither value D2 supplied from the dither mask table 54 as a carry signal to data of the upper 5 bits except the lower 3 bits of the pixel data supplied from the limited error diffusion unit 40. Supplied 5-bit pixel data is supplied to the subfield mapping unit 34.

As described above, the method and apparatus for processing video data of the PDP according to the present invention are limited by the limited error diffusion unit 40 and the dithering unit 50 to expand the pixel data extended from the initial 8 bits to 16 bits by inverse gamma correction. Dithering correction reduces the output to 5-bit pixel data. As illustrated in FIGS. 10 and 11, at least nine basic gray levels L0 to L9 may be expressed using the output 5-bit pixel data. In addition, the video data processing method and apparatus of the PDP according to the present invention may perform dithering correction using dither mask patterns as shown in FIG. 8 of the dithering unit 50, respectively, as shown in FIG. 10 between each of the nine basic gray levels L0 to L9. By subdividing the gradations of, the number of gradations that can be expressed is increased. This is made possible by a combination of spatially and temporally distributed data " 1 " such as the dither mask patterns shown in FIG. In addition, the video data processing method and apparatus of the PDP according to the present invention further increases the number of gradations that can be expressed by further subdividing the gradations subdivided by dithering correction by the limited error diffusion correction of the limited error diffusion unit 40. . As a result, the video data processing method and apparatus of the PDP according to the present invention reduces the 8-bit pixel data to 5-bit pixel data as shown in the luminance characteristic graph shown in FIG. 11 to reduce at least nine basic gray levels L0 to L9. The gray scales displayed and subdivided between the basic gray scales are represented by the above-described limited error spreading method and dithering method. Accordingly, since the address time can be sufficiently secured by reducing the number of subfields, the PDP can be driven by a single scan and the linear luminance can be realized as shown in FIG. 11, thereby minimizing the contour noise due to the difference in the emission patterns. Will be.

As described above, the video data processing method and apparatus of the PDP according to the present invention expresses the basic grayscale by reducing the number of bits of the video data input by the limited error spreading method and the dithering method, and subdividing between the basic grayscales. The grayscales are displayed by spatially and temporally distributing data using the limited error diffusion method and the dithering method.

Accordingly, according to the method and apparatus for processing video data of the PDP according to the present invention, the address time is sufficiently secured by reducing the number of subfields, so that the PDP can be driven in a single scan and the linear luminance can be realized. It can be minimized. Furthermore, according to the video data processing method and apparatus of the PDP according to the present invention, when sustaining a double scan driving of the PDP, more sustain periods can be ensured by reducing the number of subfields, thereby improving luminance.

In particular, the video data processing method and apparatus of the PDP according to the present invention can reduce the error diffusion noise by limiting the influence of the error diffusion to the dither mask pattern range of the upper gray scale.

In addition, the video data processing method and apparatus of the PDP according to the present invention can minimize dither noise such as lattice noise due to repeated dither patterns by dividing mask patterns by gray and frame by dither in the dithering method. do.

In addition, the video data processing method and apparatus of the PDP according to the present invention can minimize the dithering noise such as flicker by controlling the number of frames to be toggled for dither mask pattern selection according to the low and high gradation in the dithering method.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

1 is a perspective view illustrating a discharge cell structure of a general plasma display panel.

2 is a diagram illustrating a configuration of subfields included in one frame.

3 is a block diagram schematically illustrating a video data processing apparatus of a plasma display panel according to an exemplary embodiment of the present invention.

4 is a block diagram illustrating a detailed configuration of an error diffusion and dithering unit illustrated in FIG. 3.

FIG. 5 is a block diagram showing a specific configuration of the limited error diffusion unit shown in FIG. 4. FIG.

FIG. 6 is a view for explaining an error diffusion method of the limited error diffusion filter shown in FIG. 5; FIG.

FIG. 7 is a view for explaining a method of limiting error diffusion of the error diffusion filter shown in FIG. 5; FIG.

FIG. 8 is a diagram illustrating dither mask patterns used in the dithering unit shown in FIG. 4 as an example; FIG.

FIG. 9 is a block diagram showing a specific configuration of the dithering unit shown in FIG. 4. FIG.

FIG. 10 is a graph illustrating gradations implemented by dithering in a video data processing method according to an embodiment of the present invention; FIG.

FIG. 11 is a graph illustrating grayscales implemented by a limited error spreading and dithering method in a video data processing method according to an embodiment of the present invention; FIG.

<Brief description of symbols for the main parts of the drawings>

10: upper substrate 18: lower substrate

12A: Scanning electrode 12B: Sustaining electrode

14 upper dielectric layer 16 protective film

20: data electrode 22: lower dielectric layer

24: partition 26: phosphor

30: gamma correction unit 32: error diffusion and dithering unit

34: subfield mapping unit 36: data driver

38: PDP 40: limited error diffusion portion

42: error diffusion filter

44: random error diffusion (R-ED) coefficient generator

46: dither mask selection unit 50: dithering unit

52: mask control unit 54: dither mask table

56: adder

Claims (23)

A video data processing method of a plasma display panel for reducing the number of bits of video data by an error diffusion method and a dithering method, Limiting error diffusion of the input video data within a dither mask pattern range of an upper gray level; Dithering the limited error spread video data using a plurality of dither mask patterns divided by gray and frame. The method of claim 1, And the input video data is inverse gamma corrected video data. The method of claim 1, The limited error diffusion step Generating a first carry signal by adding error diffusion coefficients calculated by giving different weights to lower bits of some of the input video data and data of adjacent pixels; Generating a second carry signal by comparing the first carry signal with a dither value of a position corresponding to the input video data in the upper gray scale dither mask pattern; And adding the second carry signal with the remaining upper bits of the input video data to output the second carry signal. The method of claim 3, wherein Generating the first carry signal And adding a random error diffusion coefficient to the calculated error diffusion coefficients. The method of claim 3, wherein The dither mask pattern of the upper gray level may be selected from among dither mask patterns corresponding to higher gray levels than gray levels corresponding to bits of some of the input video data in a plurality of prestored dither mask patterns. How to process video data. The method of claim 3, wherein Generating the second carry signal And performing an AND operation on the first carry signal and the selected dither value to generate the second carry signal. The method of claim 1, The dithering step Selecting a dither mask pattern of a corresponding gray level among the plurality of dither mask patterns using lower bits of a part of the limited error spread video data; Selecting a dither value at a position corresponding to the limited error spread video data among the selected dither mask patterns; And adding the selected dither value to upper bits of the remaining part of the limited error spread video data. The method of claim 7, wherein Selecting the dither value And counting the vertical synchronizing signal, the horizontal synchronizing signal, and the pixel clock signal inputted from the outside, and selecting a position corresponding to the limited error spread video data by using the counted signal. Method of processing video data on display panel. The method of claim 8, Selecting the dither value And toggling dither mask patterns of different gradations for each frame based on the counted signal of the vertical synchronization signal. The method of claim 9, Selecting the dither value And comparing the limited error diffused video data with a preset reference value and reducing the number of frames to be toggled when it is smaller than the reference value. A video data processing apparatus of a plasma display panel for reducing the number of bits of video data by an error diffusion method and a dithering method, A limited error diffuser for diffusing the input video data within a range of upper gray scale dither mask patterns; And a dithering unit dithering the limited error spread video data by using a plurality of dither mask patterns divided by gray and frame. The method of claim 11, And an inverse gamma correction unit configured to output the inverse gamma correction by outputting the input video data. The method of claim 11, The limited error diffusion unit A dither mask selector for selecting a dither value of a position corresponding to the input video data in the higher gray scale dither mask pattern; Comparing the first carry signal generated by error diffusion of the input video data and the dither value, a second carry signal is generated, and the second carry signal is added to the input video data to output limited error spread video data. And an error diffusion filter for the video data processing apparatus of the plasma display panel. The method of claim 13, The dither mask selector Selecting one of dither mask patterns corresponding to higher gray levels than a gray level corresponding to some bits of the input video data from a plurality of dither mask patterns stored in the dithering unit as the upper gray level dither mask pattern A video data processing apparatus for a plasma display panel. The method of claim 13, The error diffusion filter Generating a first carry signal by adding error diffusion coefficients calculated by giving different weights to lower bits of some of the input video data and data of adjacent pixels; Generating a second carry signal by comparing the first carry signal with the dither value; And outputting the second carry signal by adding the second carry signal with the remaining upper bits of the input video data. The method of claim 13, And the error diffusion filter generates the second carry signal by performing an AND operation on the first carry signal and the selected dither value. The method of claim 13, The limited error diffusion unit And a random error diffusion coefficient generator for generating a random error diffusion coefficient to be additionally added to the calculated error diffusion coefficients. The method of claim 11, The dithering unit A dither mask table for storing the plurality of dither mask patterns and selecting and outputting a dither value corresponding to the limited error diffused video data among the stored dither mask patterns; A mask controller for indicating a position where the dither mask table corresponds to the limited error spread video data; And an adder for adding the dither value to the limited error diffused video data and outputting the dither value. The method of claim 18, The dither mask table Selecting a dither mask pattern of a corresponding gray level among the plurality of dither mask patterns by using lower bits of some of the limited error spread video data, And dither value of a position corresponding to the limited error diffused video data is selected and output from the selected dither mask pattern in response to an instruction of the mask controller. The method of claim 18, The adder is And adding the selected dither value to upper bits of the remaining part of the limited error spread video data to output the selected dither value. The method of claim 18, The mask control unit And counting the vertical synchronizing signal, the horizontal synchronizing signal, and the pixel clock signal inputted from the outside, and using the counted signal to indicate a position corresponding to the limited error diffused video data. Data processing unit. The method of claim 21, The mask control unit And instructing the dither mask table to toggle dither mask patterns of different gradations for each of the frames based on the counted signal of the vertical synchronization signal. The method of claim 22, The mask control unit And comparing the limited error spread video data with a preset reference value to reduce the number of frames to be toggled when it is smaller than the reference value.