WO2005057540A1 - Method and apparatus of processing video data for plasma display panel - Google Patents

Method and apparatus of processing video data for plasma display panel Download PDF

Info

Publication number
WO2005057540A1
WO2005057540A1 PCT/KR2004/003245 KR2004003245W WO2005057540A1 WO 2005057540 A1 WO2005057540 A1 WO 2005057540A1 KR 2004003245 W KR2004003245 W KR 2004003245W WO 2005057540 A1 WO2005057540 A1 WO 2005057540A1
Authority
WO
WIPO (PCT)
Prior art keywords
video data
dither
error diffusion
dither mask
mask patterns
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/KR2004/003245
Other languages
French (fr)
Inventor
Hwan Yu Kim
Geun Soo Lim
Dae Jin Myoung
Jun Hak Lee
Jung Hwan Kim
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
LG Electronics Inc
Original Assignee
LG Electronics Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by LG Electronics Inc filed Critical LG Electronics Inc
Publication of WO2005057540A1 publication Critical patent/WO2005057540A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/2007—Display of intermediate tones
    • G09G3/2044—Display of intermediate tones using dithering
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
    • G09G3/28—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using luminous gas-discharge panels, e.g. plasma panels
    • G09G3/288—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using luminous gas-discharge panels, e.g. plasma panels using AC panels
    • G09G3/291—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using luminous gas-discharge panels, e.g. plasma panels using AC panels controlling the gas discharge to control a cell condition, e.g. by means of specific pulse shapes
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
    • G09G3/28—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using luminous gas-discharge panels, e.g. plasma panels
    • G09G3/288—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using luminous gas-discharge panels, e.g. plasma panels using AC panels
    • G09G3/296—Driving circuits for producing the waveforms applied to the driving electrodes
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/02—Improving the quality of display appearance
    • G09G2320/0247—Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/02—Improving the quality of display appearance
    • G09G2320/0271—Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping
    • G09G2320/0276—Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/2007—Display of intermediate tones
    • G09G3/2018—Display of intermediate tones by time modulation using two or more time intervals
    • G09G3/2022—Display of intermediate tones by time modulation using two or more time intervals using sub-frames
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/2007—Display of intermediate tones
    • G09G3/2059—Display of intermediate tones using error diffusion
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
    • G09G3/28—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using luminous gas-discharge panels, e.g. plasma panels
    • G09G3/288—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using luminous gas-discharge panels, e.g. plasma panels using AC panels

Definitions

  • 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 in a plasma display panel, wherein contour noise can be reduced.
  • FIG. 1 is a perspective view illustrating the structure of a discharge cell of a conventional three-electrode AC surface discharge type PDP.
  • the discharge cell of the PDP includes a pair of sustain electrodes 1 2A, 1 2B formed on the bottom surface of an upper substrate 1 0, and a data electrode 20 formed on the top surface of a lower substrate 1 8.
  • Each of the pair of the sustain electrodes 1 2A, 1 2B has a dual layer structure of transparent electrodes and metal electrodes.
  • the sustain electrode pair 1 2A, 1 2B include a scan electrode 1 2A which receives a scan signal for an address discharge and a sustain signal for a sustain discharge as an input, and a sustain electrode 1 2B which receives a sustain signal, while operating in turn with the scan electrode 1 2A.
  • the data electrode 20 is formed in such a way to cross the pair of the sustain electrodes 1 2A, 1 2B, and supplies a data signal for the address discharge.
  • An upper dielectric layer 14 and a protection film 1 6 are laminated on the upper substrate 1 0 on which the pair of the sustain electrodes 1 2A and 1 2B are formed.
  • a lower dielectric layer 22 is formed on the lower substrate 1 8 on which the data electrode 20 is formed.
  • the upper dielectric layer 14 and the lower dielectric layer 22 serve to accumulate electric charges generated by discharging.
  • the protection film 1 6 serves to prevent damage of the upper dielectric layer 14 due to sputtering of plasma particles upon discharging, and improve emission efficiency of secondary electrons.
  • the dielectric layers 14, 22 and the protection film 1 6 serve to low an externally inputted driving voltage.
  • Barrier ribs 24 are formed over the lower substrate 1 8 on which the lower dielectric layer 22 is formed.
  • a phosphor layer 26 is formed on the lower dielectric layer 22 and the barrier ribs 24. The barrier ribs 24 serve to separate discharge spaces and to prevent ultraviolet generated by a gas discharge from leaking toward neighboring discharge spaces.
  • the phosphor layer 26 is light-emitted by the ultraviolet generated by the gas discharge, producing red (R), green (G) and blue (B) visible rays. Also, an inert gas for the gas discharge is injected into the discharge spaces.
  • This discharge cell is selected according to the address discharge by the data electrode 20 and the scan electrode 1 2A. The selected discharge cell sustains its discharge with a sustain discharge by the pair of the sustain electrodes 1 2A, 1 2B. Furthermore, the discharge cell emits the phosphor layer 26 with the ultraviolet generated in the sustain discharge, so that the phosphor layer 26 emits the R, G and B visible rays. In this case, the discharge cell implements the gray scale necessary for image display by controlling a sustain discharge period, i.e.
  • a representative method for driving this PDP is an ADS (Address and Display Separation) driving method in which the PDP is driven with one frame being divided into an address period and a display period, i.e., a sustain period.
  • ADS Address and Display Separation
  • one frame 1 F is divided into a plurality of sub-fields SF1 to SF8 corresponding to respective bits of video data.
  • Each of the sub-fields SF1 to SF8 is subdivided into a reset period RPD for initializing a discharge cell, an address period APD for selecting a discharge cell, and a sustain period SPD for maintaining discharging of a selected discharge cell.
  • the PDP implements a corresponding gray scale in such a way that different weights are assigned to the sustain periods SPD every sub-fields SF1 to SF8, and the sustain periods SPD are combined according to the video data.
  • This PDP is adapted to display an image through a pulse width modulation method in which the sustain period SPD is proportional to a video data signal.
  • display periods and non-display periods are distributed in various shapes within each frame due to sub-fields, which separate each frame according to respective bits of the video data. Accordingly, the PDP displays an image by integrating light emitted in respective sub-field periods.
  • contour noise arises due to a mismatch between the integral directions of light, which is assumed in the PDP, and a visual characteristic, which is recognized by the eye of a man.
  • contour noise increases when it has consecutive gray scales such as when the skin of a man is being displayed. For example, if gray scales light-emitted patterns of which are significantly different such as 1 27-1 28, 63-64 gray scale, 31 -32 gray scale, etc. are displayed consecutively, contour noise increases.
  • this method is disadvantageous in that it makes hardware complicated.
  • quantization error data of digital video data is calculated using a Floyd-Steinberg error diffusion filter, etc.
  • the calculated error data is assigned with different weights and are then diffused to neighboring pixels.
  • error diffusion coefficients i.e., weight
  • this method has a problem in that an error diffusion pattern occurs due to the constant error diffusion coefficients.
  • the dithering method includes adding adequate noise so that contour noise is unnoticeable to the eye of a person.
  • European Patent Application No.00250099.9 discloses a method in which three-dimensional dither patterns corresponding to a plurality of frames, a plurality of lines and a plurality of columns are repeatedly used in a PDP.
  • the conventional dithering method has a problem in that dithering noise occurs, which degrades the picture quality in specific gray scales.
  • three- dimensional dither patterns are repeatedly used while toggling them, in spite of low gray scales and high gray scales. Therefore, there occurs a problem such as flicker when representing the low gray scales.
  • the present invention has been made in view of the above problems occurring in the prior art, and it is an object of the present invention to provide a method and apparatus for processing video data in a PDP, wherein contour noise can be reduced. Another object of the present invention is to provide a method and apparatus for processing video data in a PDP, wherein error diffusion and dithering noise can be reduced. Still another object of the present invention is to provide a method and apparatus for processing video data in a PDP, wherein dithering noise of a given gray scale can be reduced.
  • a method of processing video data in a plasma display panel in which the number of bits of the video data is reduced through an error diffusion method and a dithering method, including the steps of performing a confined error diffusion process on inputted video data within the range of dither mask patterns of an upper gray scale and dithering the confined error-diffused video data using a plurality of dither mask patterns that are separated on a gray scale and frame basis .
  • the inputted video data is inverse gamma-corrected video data.
  • the step of performing the confined error diffusion process includes the steps of generating a first carry signal by adding error diffusion coefficients, which are calculated by assigning different weights to data of pixels adjacent to some of lower bits of the inputted video data; generating a second carry signal by comparing the first carry signal with a dither value at a position corresponding to the inputted video data in the dither mask patterns of the upper gray scale; and adding the second carry signal to the remaining upper bits of the inputted video data.
  • the step of generating the first carry signal includes the step of adding random error diffusion coefficients to the calculated error diffusion coefficients.
  • the dither mask patterns of the upper gray scale are selected from dither mask patterns corresponding to a gray scale, which is higher than a gray scale corresponding to some of bits of the inputted video data in a plurality of dither mask patterns that are previously stored.
  • the step of generating the second carry signal includes the step of performing an AND operation on the first carry signal and the selected dither value.
  • the dithering step includes the steps of selecting dither mask patterns of a corresponding gray scale from the plurality of the dither mask patterns by using some of lower bits of the confined error-diffused video data; selecting a dither value at a position corresponding to the confined error-diffused video data from the selected dither mask patterns; and adding the selected dither value to the remaining upper bits of the confined error-diffused video data.
  • the step of selecting the dither value includes the step of counting a vertical sync signal, a horizontal sync signal and a pixel clock signal, respectively, which are received externally, and then selecting a position corresponding to the confined error-diffused video data using the counted signals.
  • the step of selecting the dither value includes the step of toggling dither mask patterns of a corresponding gray scale, which are different on a frame basis, according to the counted signal of the vertical sync signal.
  • the step of selecting the dither value includes the step of comparing the confined error-diffused video data with a predetermined reference value, and if the confined error-diffused video data is smaller than the predetermined reference value, reducing the number of the toggled frames.
  • an apparatus for processing video data in a plasma display panel in which the number of bits of the video data is reduced through an error diffusion method and a dithering method, including a confined error diffusion unit for performing a confined error diffusion process on inputted video data within the range of dither mask patterns of an upper gray scale; and a dithering unit for dithering the confined error-diffused video data using a plurality of dither mask patterns that are separated on a gray scale and frame basis.
  • the apparatus further includes an inverse gamma correction unit for performing an inverse gamma correction process on the inputted video data.
  • the confined error diffusion unit includes a dither mask select unit for selecting a dither value at a position corresponding to the inputted video data from dither mask patterns of an upper gray scale; and an error diffusion filter for generating a second carry signal by comparing a first carry signal, which is generated by error-diffusing the inputted video data, with the dither value, and outputting confined error-diffused video data by adding the second carry signal to the inputted video data.
  • the dither mask select unit selects any one of the dither mask patterns corresponding to a gray scale, which is higher than a gray scale corresponding to some of bits of the inputted video data, from the plurality of the dither mask patterns, which are stored in the dithering unit as the dither value mask patterns of the upper gray scale.
  • the error diffusion filter generates a first carry signal by adding error diffusion coefficients, which are calculated by assigning different weights to data of pixels adjacent to some of lower bits of the inputted video data, generates a second carry signal by comparing the first carry signal with a dither value at a position corresponding to the inputted video data in the dither mask patterns of the upper gray scale, and adds the second carry signal to the remaining upper bits of the inputted video data.
  • 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 confined error diffusion unit further comprises a random error diffusion coefficient generator that generates random error diffusion coefficients that will be additionally added to the calculated error diffusion coefficients.
  • the dithering unit includes a dither mask table for storing the plurality of the dither mask patterns, and selecting a dither value corresponding to the confined error-diffused video data from the stored dither mask patterns; a mask control unit for controlling the dither mask table to indicate a position corresponding to the confined error-diffused video data; and an adder for adding the dither value to the confined error-diffused video data.
  • the dither mask table selects dither mask patterns of a corresponding gray scale from the plurality of the dither mask patterns by using some of lower bits of the confined error-diffused video data, and selects a dither value at a position corresponding to the confined error-diffused video data from the selected dither mask patterns under the control of the mask control unit.
  • the adder adds the selected dither value to the remaining upper bits of the confined error-diffused video data.
  • the mask control unit counts a vertical sync signal, a horizontal sync signal and a pixel clock signal, respectively, which are received externally, and then indicates a position corresponding to the confined error-diffused video data using the counted signals.
  • the mask control unit controls the dither mask table to select the dither value while toggling dither mask patterns of a corresponding gray scale, which are different on a frame basis, according to the counted signal of the vertical sync signal.
  • the mask control unit compares the confined error-diffused video data with a predetermined reference value, and if the confined error-diffused video data is smaller than the predetermined reference value, reduces the number of the toggled frames.
  • a method and apparatus for processing video data in a PDP in accordance with the present invention if the PDP is driven in a double scan mode, more sustain period can be secured through reduction in the number of sub-fields. Thus, the brightness can be improved. More particularly, according to a method and apparatus for processing video data in a PDP in accordance with the present invention, the effect of error diffusion is confined to the range of dither mask patterns of upper gray scales. It is thus possible to reduce error diffusion noise. Further, according to a method and apparatus for processing video data in a
  • dither mask patterns are separated on a gray scale and frame basis in a dithering method. Dithering noise such as lattice noise due to repeated dither value patterns can be thus minimized. Furthermore, according to a method and apparatus for processing video data in a PDP in accordance with the present invention, the number of frames, which are toggled in order to select dither mask patterns in the dithering method, is controlled according to low gray scales and high gray scales. Thus, dithering noise such as flicker can be minimized. It should be noted that the forgoing embodiments are merely illustrative and are not to be construed as limiting the present invention. The scope of the present invention is defined by the appended claimed rather than the detailed description of the present invention. All changes or modifications or their equivalents made within the meanings and scope of the claims should be construed as falling within the scope of the present invention.
  • FIG. 1 is a perspective view illustrating the construction of a conventional PDP;
  • FIG. 2 shows a format of sub-fields included in one frame;
  • FIG. 3 is a block diagram schematically illustrating the construction of an apparatus for processing video data in a PDP according to an embodiment of the present invention;
  • FIG. 4 is a block diagram illustrating the overall construction of the error diffusion and dithering unit shown in FIG. 3;
  • FIG. 5 is a detailed block diagram illustrating the construction of a confined error diffusion unit shown in FIG. 4;
  • FIG. 6 is a view for explaining an error diffusion method of a confined error diffusion filter shown in FIG. 5;
  • FIG. 7 is a view for explaining a confined error diffusion method of the error diffusion filter shown in FIG. 5;
  • FIG. 5 is a perspective view illustrating the construction of a conventional PDP;
  • FIG. 2 shows a format of sub-fields included in one frame;
  • FIG. 3 is a block diagram schematically illustrating the construction of an apparatus for processing
  • FIG. 8 shows an example of dither mask patterns used in the dithering unit shown in FIG. 4;
  • FIG. 9 is a block diagram illustrating the overall construction of the dithering unit shown in FIG. 4;
  • FIG. 1 0 is a graph showing gray scales implemented through dithering among the method of processing the video data according to an embodiment of the present invention; and
  • FIG. 1 1 is a graph showing gray scales implemented through a confined error diffusion and dithering method among the method of processing the video data according to an embodiment of the present invention.
  • FIG. 3 is a block diagram schematically illustrating the construction of an apparatus for processing video data in a PDP according to an embodiment of the present invention.
  • the apparatus for processing the video data in the PDP shown in FIG. 3 includes a gamma correction unit 30, an error diffusion and dithering unit 32, a sub-field mapping unit 34, and a data driving unit 38 all of which are connected between an input line of video data and a PDP 38.
  • the gamma correction unit 30 receives pixel data on which a gamma correction operation is performed so that they are suitable for a brightness characteristic of a cathode ray tube (CRT), i.e., pixel data that will be supplied to each cell (sub-pixel) constituting the PDP 38.
  • the gamma correction unit 30 performs an inverse gamma correction operation on each of the received pixel data so that the brightness characteristic depending on the pixel data has the linearity.
  • the gamma correction unit 30 outputs inverse gamma corrected pixel data corresponding to received pixel data by using a predetermined loop-up table (LUT) so that a brightness characteristic depending on pixel data complies with a 2.2 gamma curve.
  • LUT loop-up table
  • each of the pixel data outputted from the gamma correction unit 30 is composed of an integer part and a fraction part.
  • the gamma correction unit 30 outputs 1 2-bit corrected pixel data having a 6-bit integer part and a 6-bit fraction part, or 1 6-bit corrected pixel data having a 8-bit integer part and a 8-bit fraction part.
  • the error diffusion and dithering unit 32 corrects each of pixel data received from the gamma correction unit 30 through an error diffusion method and a dithering method using dither mask patterns, and thus outputs pixel data the number of bits is reduced.
  • the error diffusion and dithering unit 32 confines the effect of the error diffusion to a gray scale range of upper dither mask patterns, thereby reducing error diffusion noise and dither noise, such as flicker.
  • the sub-field mapping unit 34 maps each of the pixel data received from the error diffusion and dithering unit 32 to a predetermined sub-field pattern, and outputs the mapped pixel data.
  • the data driving unit 36 latches the data, which are separated on a big basis according to the sub-field pattern and then received from the sub-field mapping unit 34, and supplies the latched data to address electrode lines of the PDP 38, on one line basis, every period where one horizontal line is driven.
  • the PDP 38 includes address electrode lines, and a sustain electrode line pair that crosses the address electrode lines with a discharge space intervened therebetween. Cells having the discharge spaces, which correspond to sub-pixels, are formed every intersection where the address electrode lines and the pair of the sustain electrode lines cross.
  • This PDP 38 selects cells to be turned on through an address discharging depending on data, which will be supplied from the data driving unit 36 to the address electrode lines whenever the scan electrode lines among the sustain electrode line pair are driven in an address period of each sub- field. Further, the PDP 38 allows the selected cells to maintain discharging in a sustain period of each sub-field by driving the sustain electrode line pair.
  • FIG. 4 is a block diagram illustrating the overall construction of the error diffusion and dithering unit 32 shown in FIG. 3.
  • the error diffusion and dithering unit 32 includes a confined error diffusion unit 40 and a dithering unit 42.
  • the confined error diffusion unit 40 performs an error diffusion operation on the video data from the gamma correction unit 30 and error diffusion coefficients of neighboring pixels, which are calculated through the error diffusion filter, and thus outputs pixel data the number of bits is reduced.
  • the confined error diffusion unit 40 adds random error diffusion (hereinafter, referred to as "R- ED") coefficients to the error diffusion operation so as to prevent error diffusion patterns from occurring due to constant error diffusion coefficients. Moreover, the confined error diffusion unit 40 confines the effect of the error diffusion to the range of dither mask patterns of upper gray scales by using dither mask patterns used in the dithering unit 50. To this end, the confined error diffusion unit 40 includes an error diffusion filter 42, and a R-ED coefficient generator 44 and a dither mask select unit 46 both of which are connected to the error diffusion filter 42, as shown in FIG. 5.
  • R- ED random error diffusion
  • the error diffusion filter 42 includes error diffusion operators (not shown) for error diffusion, and line memory (not shown) for storing some lower bits to be used in the error diffusion among neighboring pixel data, e.g., fraction parts.
  • error diffusion operators not shown
  • line memory not shown
  • some lower bits to be used in the error diffusion among neighboring pixel data e.g., fraction parts.
  • the error diffusion filter 42 stores lower 8-bit data corresponding to the fraction part among the 1 6 bits in the line memory so that the 8-bit data can be used for the error diffusion operation of pixels adjacent to the 8-bit data.
  • the error diffusion filter 42 reads the fraction parts of the neighboring pixel data, which are stored in the line memory, and assigns different weights to the fraction parts depending upon the locations of the pixels, thus calculating error diffusion coefficients. For example, if an error diffusion operation is performed on a current pixel
  • the error diffusion filter 42 calculates error diffusion coefficients for respective pixels P1 to P4 by assigning a weight of 1 /1 6 to a fraction part of the pixel P1 adjacent to the pixel P5, a weight of 5/1 6 to a fraction part of the pixel P2, a weight of 3/1 6 to a fraction part of the pixel P3 and a weight of 7/1 6 to a fraction part of the pixel P4.
  • the error diffusion filter 42 adds the error diffusion coefficients of the neighboring pixels P1 to P4 and the R-ED coefficient R generated from the R-ED coefficient generator 44 to the fraction part (low 8 bits) of the current pixel P6 data, thereby generating a first carry signal "0" or "1 ".
  • the error diffusion filter 42 confines the effect of the error diffusion to the range of the dither mask patterns of the upper gray scales among the dither mask patterns used in the dithering unit 50.
  • the error diffusion filter 42 compares an initial carry signal (hereinafter, referred to as "first carry signal”), which is generated through the error diffusion method that is performed on the current pixel data, and a dither value D1 from the dither mask select unit 46, and then outputs a last error diffusion carry signal (hereinafter, referred to as "second carry signal”) "0" or " 1 ", which will be added to upper some of bits of current pixel data, e.g., integer parts (upper 8 bits).
  • the dither mask select unit 46 selects dither mask patterns, which belong to gray scales higher than lower 3 bits, from the dither mask patterns stored in the dithering unit 50, by using some of bits of the current pixel data inputted to the error diffusion filter 42, e.g., lower 3 bits of the integer parts. For example, if lower 3 bits of an integer part of pixel data that is currently inputted are "01 0", i.e., if the lower 3 bits belong to gray scales of 2/8 as shown in FIG.
  • the dither mask select unit 46 selects any one of gray scales of 3/8 to 7/8, which are higher than the gray scales of 2/8, e.g., a dither mask pattern corresponding to the gray scales of 4/8.
  • the dither mask select unit 46 selects a dither value D1 corresponding to the position of a current pixel data of a current frame from dither mask patterns for four frames 1 F to 4F, which correspond to the gray scales of 4/8, among a plurality of dither mask patterns stored in the dithering unit 50, as shown in FIG.
  • the error diffusion filter 42 compares the dither value D 1 received from the dither mask select unit 46 with the first carry signal generated through the error diffusion to generate the second carry signal. It adds the generated second carry signal to the integer part (upper 8 bits) of the current pixel data to generate 8-bit pixel data. In the concrete, if the first carry signal generated through the error diffusion is " 1 " and the dither value D 1 from the dither mask select unit 46 is " 1 ", the error diffusion filter 42 generates the second carry signal of " 1 " .
  • the error diffusion filter 42 If the first carry signal generated through the error diffusion is not “ 1 " and the dither value D 1 from the dither mask select unit 46 is not “ 1 ", the error diffusion filter 42 generates the second carry signal of "0" . In other words, the error diffusion filter 42 performs an AND operation on the first carry signal generated through the error diffusion and the dither value D 1 from the dither mask select unit 46 to generate the second carry signal. Accordingly, the position of a pixel where the second carry signal " 1 " generated through the error diffusion in the error diffusion filter 42 is added to pixel data is confined to the position set to "1 " in dither mask patterns of gray scale, which are higher than lower 3 bits among the pixel data, as indicated by a bold line in FIG. 7.
  • FIG. 9 is a block diagram illustrating the overall construction of the dithering unit 50 shown in FIG. 4.
  • the dithering unit 50 includes a dither mask table 54 that is connected to a dither mask control unit 52 and an output line of the confined error diffusion unit 40, and an adder 56 that is connected to the dither mask table 54 and the output line of the confined error diffusion unit 40.
  • the dither mask table 54 stores different dither mask patterns on a gray scale and frame basis. For instance, as shown in FIG.
  • dither mask patterns having a cell (sub-pixel) size of 4 x 4 are separated on eight gray scale basis, such as 0 to 7/8, corresponding to lower 3 bits of pixel data, and each of the eight dither mask patterns is again separated on four frames 1 F to 4F basis.
  • the dither mask table 54 stores a total of the 32 dither mask patterns. From FIG. 8, it can be seen that the number of cells, which are set to the dither value "1 " in each of the dither mask patterns of the gray scales 0, 1 /8, 2/8, 3/8, 4/8, 5/8, 6/8, 7/8 and 7/8, increases in the order of 0, 2, 4, 6, 8, 10, 1 2 and 1 4 in number.
  • the positions of the cells, which are set to the dither value "1 " are different on four frames 1 F to 4F basis.
  • the position of " 1 " can vary in various manners according to a designer, if needed.
  • the positions of on-cells corresponding to the dither value " 1 " can be controlled spatially and temporally according to these dither mask patterns.
  • dithering noise such as grating noise, which is caused by the repetition of constant dither mask patterns, can be reduced.
  • the dither mask table 54 in which these dither mask patterns are stored receives some of lower bits of the pixel data received from the confined error diffusion unit 40, e.g., 3 bits of 8-bit pixel data.
  • the dither mask table 54 selects a dither mask pattern of a gray scale that corresponds to the received lower 3 bits from the dither mask patterns as shown in FIG. 8. Then, the dither mask table 54 selects a dither value D2, which corresponds to a frame and the position of a cell, which are indicated by the dither mask control unit 52, from the dither mask patterns of the selected gray scale, and then outputs the selected dither value D2 to the adder 56.
  • the dither mask control unit 52 counts the vertical sync signal V, which is received from an external controller (not shown), to indicate a corresponding frame of the four frames 1 F to 4F, and counts the horizontal sync signal H and the pixel clock signal P to indicate a horizontal line and a vertical line within the corresponding frame, i.e., the position of a cell.
  • the dither mask control unit 52 controls the dither mask table 54 using the counted signal of the vertical sync signal V, so that the dither mask table 54 selects a dither mask pattern of a corresponding gray scale while toggling the first to fourth frames 1 F to F4.
  • the dither mask control unit 52 controls the number of frames, which are toggled in the dither mask table 54, according to a gray scale of received pixel data.
  • the dither mask control unit 52 compares pixel data that is received from the confined error diffusion unit 40 with a predetermined reference value to determine whether the received pixel data is low gray scale data or high gray scale data. In this time, if it is determined that the received pixel data is the high gray scale data, the dither mask control unit 52 controls the dither mask table 54 to select the dither mask pattern while toggling three frames or four frames 1 F to 4F, as described above.
  • the dither mask control unit 52 controls the dither mask table 54 to select the dither mask pattern while toggling two frames of the four frames 1 F to 4F. Accordingly, if the low gray scale pixel data is consistently displayed during a plurality of frames, it is possible to prevent a flicker phenomenon that is generated due to different dither mask patterns on a frame basis.
  • the adder 56 adds the dither value D2, which is received from the dither mask table 54, to data of upper 5 bits except for lower 3 bits among the pixel data, which is received from the confined error diffusion unit 40, as a carry signal, and thus supplies the corrected 5-bit pixel data to the sub-field mapping unit 34.
  • pixel data which is expanded from initial 8 bits to 16 bits through the inverse gamma correction operation, is reduced to 5-bit pixel data through the confined error diffusion operation of the confined error diffusion unit 40 and the dithering correction operation of the dithering unit 50. Therefore, nine or more basic gray scales LO to L9, as shown in FIGS. 1 0 and 1 1 , can be represented using the 5-bit pixel data. Furthermore, according to the method and apparatus for processing the video data in the PDP in accordance with the present invention, as shown in FIG.
  • the gray scales between the nine or more basic gray scales L0 to L9 are subdivided through the dithering correction using the dither mask patterns as shown in FIG. 8.
  • the number of gray scales that can be represented increases. This is made possible through a combination of data "1 ", which are variously distributed spatially and temporally, like the dither mask patterns shown in FIG. 8.
  • between-gray scales, which are subdivided through the dithering correction operation are further subdivided through confined error diffusion correction of the confined error diffusion unit 40. It is thus possible to further increase the number of gray scales, which can be represented.
  • 8-bit pixel data is reduced to 5-bit pixel data to represent nine or more basic gray scales LO to L9, as illustrated in a brightness characteristic graph of FIG. 1 1 , and gray scales subdivided between the basic gray scales are represented through the confined error diffusion operation and the dithering operation. Accordingly, since an address time can be sufficiently secured due to a reduction in the number of sub-fields, a PDP can be driven in a single scan mode, and linear brightness can be implemented, as shown in FIG. 1 1 . It is thus possible to minimize contour noise due to a difference in light emission patterns.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Power Engineering (AREA)
  • Plasma & Fusion (AREA)
  • Control Of Indicators Other Than Cathode Ray Tubes (AREA)
  • Control Of Gas Discharge Display Tubes (AREA)

Abstract

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 in a plasma display panel, wherein contour noise can be reduced. The method of processing the video data in the plasma display panel in which the number of bits of the video data is reduced through an error diffusion method and a dithering method includes the steps of performing a confined error diffusion process on inputted video data within the range of dither mask patterns of an upper gray scale, and dithering the confined error-diffused video data using a plurality of dither mask patterns that are separated on a gray scale and frame basis.

Description

METHOD AND APPARATUS OF PROCESSING VIDEO DATA FOR PLASMA DISPLAY PANEL
Technical Field 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 in a plasma display panel, wherein contour noise can be reduced.
Background Art A plasma display panel (hereinafter, referred to as "PDP"), which can be easily made large, has attracted public attention as a flat panel display device. The PDP is adapted to display an image by controlling a gas discharge period of each of pixels according to digital video data. A representative PDP is one, which has three electrodes and is driven with an AC voltage, as shown in FIG. 1 . FIG.1 is a perspective view illustrating the structure of a discharge cell of a conventional three-electrode AC surface discharge type PDP. Referring to FIG. 1 , the discharge cell of the PDP includes a pair of sustain electrodes 1 2A, 1 2B formed on the bottom surface of an upper substrate 1 0, and a data electrode 20 formed on the top surface of a lower substrate 1 8. Each of the pair of the sustain electrodes 1 2A, 1 2B has a dual layer structure of transparent electrodes and metal electrodes. The sustain electrode pair 1 2A, 1 2B include a scan electrode 1 2A which receives a scan signal for an address discharge and a sustain signal for a sustain discharge as an input, and a sustain electrode 1 2B which receives a sustain signal, while operating in turn with the scan electrode 1 2A. The data electrode 20 is formed in such a way to cross the pair of the sustain electrodes 1 2A, 1 2B, and supplies a data signal for the address discharge. An upper dielectric layer 14 and a protection film 1 6 are laminated on the upper substrate 1 0 on which the pair of the sustain electrodes 1 2A and 1 2B are formed. A lower dielectric layer 22 is formed on the lower substrate 1 8 on which the data electrode 20 is formed. The upper dielectric layer 14 and the lower dielectric layer 22 serve to accumulate electric charges generated by discharging. The protection film 1 6 serves to prevent damage of the upper dielectric layer 14 due to sputtering of plasma particles upon discharging, and improve emission efficiency of secondary electrons. The dielectric layers 14, 22 and the protection film 1 6 serve to low an externally inputted driving voltage. Barrier ribs 24 are formed over the lower substrate 1 8 on which the lower dielectric layer 22 is formed. A phosphor layer 26 is formed on the lower dielectric layer 22 and the barrier ribs 24. The barrier ribs 24 serve to separate discharge spaces and to prevent ultraviolet generated by a gas discharge from leaking toward neighboring discharge spaces. The phosphor layer 26 is light-emitted by the ultraviolet generated by the gas discharge, producing red (R), green (G) and blue (B) visible rays. Also, an inert gas for the gas discharge is injected into the discharge spaces. This discharge cell is selected according to the address discharge by the data electrode 20 and the scan electrode 1 2A. The selected discharge cell sustains its discharge with a sustain discharge by the pair of the sustain electrodes 1 2A, 1 2B. Furthermore, the discharge cell emits the phosphor layer 26 with the ultraviolet generated in the sustain discharge, so that the phosphor layer 26 emits the R, G and B visible rays. In this case, the discharge cell implements the gray scale necessary for image display by controlling a sustain discharge period, i.e. , the number of sustain discharges according to video data. Moreover, a combination of three discharge cells on which the R, G and B phosphors 26 are respectively coated implements the colors of one pixel. A representative method for driving this PDP is an ADS (Address and Display Separation) driving method in which the PDP is driven with one frame being divided into an address period and a display period, i.e., a sustain period. In the ADS driving method, one frame 1 F is divided into a plurality of sub-fields SF1 to SF8 corresponding to respective bits of video data. Each of the sub-fields SF1 to SF8 is subdivided into a reset period RPD for initializing a discharge cell, an address period APD for selecting a discharge cell, and a sustain period SPD for maintaining discharging of a selected discharge cell. In this time, the PDP implements a corresponding gray scale in such a way that different weights are assigned to the sustain periods SPD every sub-fields SF1 to SF8, and the sustain periods SPD are combined according to the video data. This PDP is adapted to display an image through a pulse width modulation method in which the sustain period SPD is proportional to a video data signal. In this case, display periods and non-display periods are distributed in various shapes within each frame due to sub-fields, which separate each frame according to respective bits of the video data. Accordingly, the PDP displays an image by integrating light emitted in respective sub-field periods. In this case, contour noise arises due to a mismatch between the integral directions of light, which is assumed in the PDP, and a visual characteristic, which is recognized by the eye of a man. Moreover, contour noise increases when it has consecutive gray scales such as when the skin of a man is being displayed. For example, if gray scales light-emitted patterns of which are significantly different such as 1 27-1 28, 63-64 gray scale, 31 -32 gray scale, etc. are displayed consecutively, contour noise increases. In order to reduce such contour noise, methods such as a method of optimizing the sequence of sub-fields, a method of dividing sub-fields corresponding to the most significant bit (MSB), an equalizing pulse method, an error diffusion method and a dithering method were proposed. Of them, the equalizing pulse method, the error diffusion method and the dithering method are the most frequently used methods. For example, in the equalizing pulse method, video data that causes contour noise is increased or decreased by using an equalizing pulse, thus compensating for the video data. In this method, however, a motion estimator is required since contour noise is related to motion. Furthermore, a memory having a large capacity, which can store a plurality of look-up tables, must be equipped because a different equalizing pulse is necessary depending upon the motion rate. Therefore, this method is disadvantageous in that it makes hardware complicated. In the error diffusion method, quantization error data of digital video data is calculated using a Floyd-Steinberg error diffusion filter, etc., the calculated error data is assigned with different weights and are then diffused to neighboring pixels. In the error diffusion method, however, since error diffusion coefficients (i.e., weight) for neighboring pixels are set to be constant, they are repeated on a line and frame basis. Accordingly, this method has a problem in that an error diffusion pattern occurs due to the constant error diffusion coefficients. The dithering method includes adding adequate noise so that contour noise is unnoticeable to the eye of a person. For example, European Patent Application No.00250099.9 discloses a method in which three-dimensional dither patterns corresponding to a plurality of frames, a plurality of lines and a plurality of columns are repeatedly used in a PDP. The conventional dithering method, however, has a problem in that dithering noise occurs, which degrades the picture quality in specific gray scales. Furthermore, in the conventional dithering method, three- dimensional dither patterns are repeatedly used while toggling them, in spite of low gray scales and high gray scales. Therefore, there occurs a problem such as flicker when representing the low gray scales.
Disclosure of Invention Technical Problem Accordingly, the present invention has been made in view of the above problems occurring in the prior art, and it is an object of the present invention to provide a method and apparatus for processing video data in a PDP, wherein contour noise can be reduced. Another object of the present invention is to provide a method and apparatus for processing video data in a PDP, wherein error diffusion and dithering noise can be reduced. Still another object of the present invention is to provide a method and apparatus for processing video data in a PDP, wherein dithering noise of a given gray scale can be reduced.
Technical Solution To achieve the above objects, according to the present invention, there is provided a method of processing video data in a plasma display panel in which the number of bits of the video data is reduced through an error diffusion method and a dithering method, including the steps of performing a confined error diffusion process on inputted video data within the range of dither mask patterns of an upper gray scale and dithering the confined error-diffused video data using a plurality of dither mask patterns that are separated on a gray scale and frame basis . The inputted video data is inverse gamma-corrected video data. The step of performing the confined error diffusion process includes the steps of generating a first carry signal by adding error diffusion coefficients, which are calculated by assigning different weights to data of pixels adjacent to some of lower bits of the inputted video data; generating a second carry signal by comparing the first carry signal with a dither value at a position corresponding to the inputted video data in the dither mask patterns of the upper gray scale; and adding the second carry signal to the remaining upper bits of the inputted video data. The step of generating the first carry signal includes the step of adding random error diffusion coefficients to the calculated error diffusion coefficients. The dither mask patterns of the upper gray scale are selected from dither mask patterns corresponding to a gray scale, which is higher than a gray scale corresponding to some of bits of the inputted video data in a plurality of dither mask patterns that are previously stored. The step of generating the second carry signal includes the step of performing an AND operation on the first carry signal and the selected dither value. The dithering step includes the steps of selecting dither mask patterns of a corresponding gray scale from the plurality of the dither mask patterns by using some of lower bits of the confined error-diffused video data; selecting a dither value at a position corresponding to the confined error-diffused video data from the selected dither mask patterns; and adding the selected dither value to the remaining upper bits of the confined error-diffused video data. The step of selecting the dither value includes the step of counting a vertical sync signal, a horizontal sync signal and a pixel clock signal, respectively, which are received externally, and then selecting a position corresponding to the confined error-diffused video data using the counted signals. The step of selecting the dither value includes the step of toggling dither mask patterns of a corresponding gray scale, which are different on a frame basis, according to the counted signal of the vertical sync signal. The step of selecting the dither value includes the step of comparing the confined error-diffused video data with a predetermined reference value, and if the confined error-diffused video data is smaller than the predetermined reference value, reducing the number of the toggled frames. According to the present invention, there is provided an apparatus for processing video data in a plasma display panel in which the number of bits of the video data is reduced through an error diffusion method and a dithering method, including a confined error diffusion unit for performing a confined error diffusion process on inputted video data within the range of dither mask patterns of an upper gray scale; and a dithering unit for dithering the confined error-diffused video data using a plurality of dither mask patterns that are separated on a gray scale and frame basis. The apparatus further includes an inverse gamma correction unit for performing an inverse gamma correction process on the inputted video data. The confined error diffusion unit includes a dither mask select unit for selecting a dither value at a position corresponding to the inputted video data from dither mask patterns of an upper gray scale; and an error diffusion filter for generating a second carry signal by comparing a first carry signal, which is generated by error-diffusing the inputted video data, with the dither value, and outputting confined error-diffused video data by adding the second carry signal to the inputted video data. The dither mask select unit selects any one of the dither mask patterns corresponding to a gray scale, which is higher than a gray scale corresponding to some of bits of the inputted video data, from the plurality of the dither mask patterns, which are stored in the dithering unit as the dither value mask patterns of the upper gray scale. The error diffusion filter generates a first carry signal by adding error diffusion coefficients, which are calculated by assigning different weights to data of pixels adjacent to some of lower bits of the inputted video data, generates a second carry signal by comparing the first carry signal with a dither value at a position corresponding to the inputted video data in the dither mask patterns of the upper gray scale, and adds the second carry signal to the remaining upper bits of the inputted video data. 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 confined error diffusion unit further comprises a random error diffusion coefficient generator that generates random error diffusion coefficients that will be additionally added to the calculated error diffusion coefficients. The dithering unit includes a dither mask table for storing the plurality of the dither mask patterns, and selecting a dither value corresponding to the confined error-diffused video data from the stored dither mask patterns; a mask control unit for controlling the dither mask table to indicate a position corresponding to the confined error-diffused video data; and an adder for adding the dither value to the confined error-diffused video data. The dither mask table selects dither mask patterns of a corresponding gray scale from the plurality of the dither mask patterns by using some of lower bits of the confined error-diffused video data, and selects a dither value at a position corresponding to the confined error-diffused video data from the selected dither mask patterns under the control of the mask control unit. The adder adds the selected dither value to the remaining upper bits of the confined error-diffused video data. The mask control unit counts a vertical sync signal, a horizontal sync signal and a pixel clock signal, respectively, which are received externally, and then indicates a position corresponding to the confined error-diffused video data using the counted signals. The mask control unit controls the dither mask table to select the dither value while toggling dither mask patterns of a corresponding gray scale, which are different on a frame basis, according to the counted signal of the vertical sync signal. The mask control unit compares the confined error-diffused video data with a predetermined reference value, and if the confined error-diffused video data is smaller than the predetermined reference value, reduces the number of the toggled frames.
Advantageous Effects As described above, according to a method and apparatus for processing video data in a PDP in accordance with the present invention, basic gray scales are represented using inputted video data the number of bits of which is reduced through a confined error diffusion method and a dithering method. Gray scales, which are subdivided between the basic gray scales, are represented by distributing data spatially and temporally by means of the confined error diffusion method and the dithering method. Accordingly, according to a method and apparatus for processing video data in a PDP in accordance with the present invention, since an address time can be sufficiently secured due to a reduction in the number of sub-fields, the PDP can be driven in a single scan mode, and linear brightness can be implemented. It is thus possible to minimize contour noise. Furthermore, according to a method and apparatus for processing video data in a PDP in accordance with the present invention, if the PDP is driven in a double scan mode, more sustain period can be secured through reduction in the number of sub-fields. Thus, the brightness can be improved. More particularly, according to a method and apparatus for processing video data in a PDP in accordance with the present invention, the effect of error diffusion is confined to the range of dither mask patterns of upper gray scales. It is thus possible to reduce error diffusion noise. Further, according to a method and apparatus for processing video data in a
PDP in accordance with the present invention, dither mask patterns are separated on a gray scale and frame basis in a dithering method. Dithering noise such as lattice noise due to repeated dither value patterns can be thus minimized. Furthermore, according to a method and apparatus for processing video data in a PDP in accordance with the present invention, the number of frames, which are toggled in order to select dither mask patterns in the dithering method, is controlled according to low gray scales and high gray scales. Thus, dithering noise such as flicker can be minimized. It should be noted that the forgoing embodiments are merely illustrative and are not to be construed as limiting the present invention. The scope of the present invention is defined by the appended claimed rather than the detailed description of the present invention. All changes or modifications or their equivalents made within the meanings and scope of the claims should be construed as falling within the scope of the present invention.
Brief Description of Drawings FIG. 1 is a perspective view illustrating the construction of a conventional PDP; FIG. 2 shows a format of sub-fields included in one frame; FIG. 3 is a block diagram schematically illustrating the construction of an apparatus for processing video data in a PDP according to an embodiment of the present invention; FIG. 4 is a block diagram illustrating the overall construction of the error diffusion and dithering unit shown in FIG. 3; FIG. 5 is a detailed block diagram illustrating the construction of a confined error diffusion unit shown in FIG. 4; FIG. 6 is a view for explaining an error diffusion method of a confined error diffusion filter shown in FIG. 5; FIG. 7 is a view for explaining a confined error diffusion method of the error diffusion filter shown in FIG. 5; FIG. 8 shows an example of dither mask patterns used in the dithering unit shown in FIG. 4; FIG. 9 is a block diagram illustrating the overall construction of the dithering unit shown in FIG. 4; FIG. 1 0 is a graph showing gray scales implemented through dithering among the method of processing the video data according to an embodiment of the present invention; and FIG. 1 1 is a graph showing gray scales implemented through a confined error diffusion and dithering method among the method of processing the video data according to an embodiment of the present invention.
Best Mode for Carrying Out the Invention The present invention will now be described in detail in connection with preferred embodiments with reference to FIGS. 3 to 1 1 . FIG. 3 is a block diagram schematically illustrating the construction of an apparatus for processing video data in a PDP according to an embodiment of the present invention. The apparatus for processing the video data in the PDP shown in FIG. 3 includes a gamma correction unit 30, an error diffusion and dithering unit 32, a sub-field mapping unit 34, and a data driving unit 38 all of which are connected between an input line of video data and a PDP 38. The gamma correction unit 30 receives pixel data on which a gamma correction operation is performed so that they are suitable for a brightness characteristic of a cathode ray tube (CRT), i.e., pixel data that will be supplied to each cell (sub-pixel) constituting the PDP 38. The gamma correction unit 30 performs an inverse gamma correction operation on each of the received pixel data so that the brightness characteristic depending on the pixel data has the linearity. For example, the gamma correction unit 30 outputs inverse gamma corrected pixel data corresponding to received pixel data by using a predetermined loop-up table (LUT) so that a brightness characteristic depending on pixel data complies with a 2.2 gamma curve. In this case, each of the pixel data outputted from the gamma correction unit 30 is composed of an integer part and a fraction part. For example, if 8-bit pixel data is received, the gamma correction unit 30 outputs 1 2-bit corrected pixel data having a 6-bit integer part and a 6-bit fraction part, or 1 6-bit corrected pixel data having a 8-bit integer part and a 8-bit fraction part. The error diffusion and dithering unit 32 corrects each of pixel data received from the gamma correction unit 30 through an error diffusion method and a dithering method using dither mask patterns, and thus outputs pixel data the number of bits is reduced. In this case, the error diffusion and dithering unit 32 confines the effect of the error diffusion to a gray scale range of upper dither mask patterns, thereby reducing error diffusion noise and dither noise, such as flicker. Detailed description on the error diffusion and dithering unit 32 will be given later on. The sub-field mapping unit 34 maps each of the pixel data received from the error diffusion and dithering unit 32 to a predetermined sub-field pattern, and outputs the mapped pixel data. The data driving unit 36 latches the data, which are separated on a big basis according to the sub-field pattern and then received from the sub-field mapping unit 34, and supplies the latched data to address electrode lines of the PDP 38, on one line basis, every period where one horizontal line is driven. The PDP 38 includes address electrode lines, and a sustain electrode line pair that crosses the address electrode lines with a discharge space intervened therebetween. Cells having the discharge spaces, which correspond to sub-pixels, are formed every intersection where the address electrode lines and the pair of the sustain electrode lines cross. This PDP 38 selects cells to be turned on through an address discharging depending on data, which will be supplied from the data driving unit 36 to the address electrode lines whenever the scan electrode lines among the sustain electrode line pair are driven in an address period of each sub- field. Further, the PDP 38 allows the selected cells to maintain discharging in a sustain period of each sub-field by driving the sustain electrode line pair. In this case, since the number of sub-fields constituting one frame is reduced as many as the number of bits of video data by means of the error diffusion and dithering unit 32, the address period can be sufficiently secured. It is thus possible to drive the PDP 38 even with a single scan method. FIG. 4 is a block diagram illustrating the overall construction of the error diffusion and dithering unit 32 shown in FIG. 3. The error diffusion and dithering unit 32 includes a confined error diffusion unit 40 and a dithering unit 42. The confined error diffusion unit 40 performs an error diffusion operation on the video data from the gamma correction unit 30 and error diffusion coefficients of neighboring pixels, which are calculated through the error diffusion filter, and thus outputs pixel data the number of bits is reduced. In this time, the confined error diffusion unit 40 adds random error diffusion (hereinafter, referred to as "R- ED") coefficients to the error diffusion operation so as to prevent error diffusion patterns from occurring due to constant error diffusion coefficients. Moreover, the confined error diffusion unit 40 confines the effect of the error diffusion to the range of dither mask patterns of upper gray scales by using dither mask patterns used in the dithering unit 50. To this end, the confined error diffusion unit 40 includes an error diffusion filter 42, and a R-ED coefficient generator 44 and a dither mask select unit 46 both of which are connected to the error diffusion filter 42, as shown in FIG. 5. The error diffusion filter 42 includes error diffusion operators (not shown) for error diffusion, and line memory (not shown) for storing some lower bits to be used in the error diffusion among neighboring pixel data, e.g., fraction parts. In the concrete, assuming that pixel data of 1 6 bits (integer part 8-bit, fraction part 8-bit) are received from the first gamma correction unit 30, the error diffusion filter 42 stores lower 8-bit data corresponding to the fraction part among the 1 6 bits in the line memory so that the 8-bit data can be used for the error diffusion operation of pixels adjacent to the 8-bit data. Furthermore, the error diffusion filter 42 reads the fraction parts of the neighboring pixel data, which are stored in the line memory, and assigns different weights to the fraction parts depending upon the locations of the pixels, thus calculating error diffusion coefficients. For example, if an error diffusion operation is performed on a current pixel
P5, as shown in FIG. 6, the error diffusion filter 42 calculates error diffusion coefficients for respective pixels P1 to P4 by assigning a weight of 1 /1 6 to a fraction part of the pixel P1 adjacent to the pixel P5, a weight of 5/1 6 to a fraction part of the pixel P2, a weight of 3/1 6 to a fraction part of the pixel P3 and a weight of 7/1 6 to a fraction part of the pixel P4. The error diffusion filter 42 adds the error diffusion coefficients of the neighboring pixels P1 to P4 and the R-ED coefficient R generated from the R-ED coefficient generator 44 to the fraction part (low 8 bits) of the current pixel P6 data, thereby generating a first carry signal "0" or "1 ". Furthermore, the error diffusion filter 42 confines the effect of the error diffusion to the range of the dither mask patterns of the upper gray scales among the dither mask patterns used in the dithering unit 50. In the concrete, the error diffusion filter 42 compares an initial carry signal (hereinafter, referred to as "first carry signal"), which is generated through the error diffusion method that is performed on the current pixel data, and a dither value D1 from the dither mask select unit 46, and then outputs a last error diffusion carry signal (hereinafter, referred to as "second carry signal") "0" or " 1 ", which will be added to upper some of bits of current pixel data, e.g., integer parts (upper 8 bits). To this end, the dither mask select unit 46 selects dither mask patterns, which belong to gray scales higher than lower 3 bits, from the dither mask patterns stored in the dithering unit 50, by using some of bits of the current pixel data inputted to the error diffusion filter 42, e.g., lower 3 bits of the integer parts. For example, if lower 3 bits of an integer part of pixel data that is currently inputted are "01 0", i.e., if the lower 3 bits belong to gray scales of 2/8 as shown in FIG. 7, the dither mask select unit 46 selects any one of gray scales of 3/8 to 7/8, which are higher than the gray scales of 2/8, e.g., a dither mask pattern corresponding to the gray scales of 4/8. In this case, the dither mask select unit 46 selects a dither value D1 corresponding to the position of a current pixel data of a current frame from dither mask patterns for four frames 1 F to 4F, which correspond to the gray scales of 4/8, among a plurality of dither mask patterns stored in the dithering unit 50, as shown in FIG. 8, by using a vertical sync signal V, a horizontal sync signal H and a pixel clock signal P, which are received externally, and then supplies the selected dither value D1 to the error diffusion filter 42. Accordingly, the error diffusion filter 42 compares the dither value D 1 received from the dither mask select unit 46 with the first carry signal generated through the error diffusion to generate the second carry signal. It adds the generated second carry signal to the integer part (upper 8 bits) of the current pixel data to generate 8-bit pixel data. In the concrete, if the first carry signal generated through the error diffusion is " 1 " and the dither value D 1 from the dither mask select unit 46 is " 1 ", the error diffusion filter 42 generates the second carry signal of " 1 " . If the first carry signal generated through the error diffusion is not " 1 " and the dither value D 1 from the dither mask select unit 46 is not " 1 ", the error diffusion filter 42 generates the second carry signal of "0" . In other words, the error diffusion filter 42 performs an AND operation on the first carry signal generated through the error diffusion and the dither value D 1 from the dither mask select unit 46 to generate the second carry signal. Accordingly, the position of a pixel where the second carry signal " 1 " generated through the error diffusion in the error diffusion filter 42 is added to pixel data is confined to the position set to "1 " in dither mask patterns of gray scale, which are higher than lower 3 bits among the pixel data, as indicated by a bold line in FIG. 7. As a result, since the effect of the error diffusion in the error diffusion filter 42 is confined to the range of the dither mask patterns of the upper gray scales, it is possible to minimize noise such as the flicker phenomenon due to error diffusion. FIG. 9 is a block diagram illustrating the overall construction of the dithering unit 50 shown in FIG. 4. The dithering unit 50 includes a dither mask table 54 that is connected to a dither mask control unit 52 and an output line of the confined error diffusion unit 40, and an adder 56 that is connected to the dither mask table 54 and the output line of the confined error diffusion unit 40. The dither mask table 54 stores different dither mask patterns on a gray scale and frame basis. For instance, as shown in FIG. 8, dither mask patterns having a cell (sub-pixel) size of 4 x 4 are separated on eight gray scale basis, such as 0 to 7/8, corresponding to lower 3 bits of pixel data, and each of the eight dither mask patterns is again separated on four frames 1 F to 4F basis. Thus, the dither mask table 54 stores a total of the 32 dither mask patterns. From FIG. 8, it can be seen that the number of cells, which are set to the dither value "1 " in each of the dither mask patterns of the gray scales 0, 1 /8, 2/8, 3/8, 4/8, 5/8, 6/8, 7/8 and 7/8, increases in the order of 0, 2, 4, 6, 8, 10, 1 2 and 1 4 in number. It can be also known that the positions of the cells, which are set to the dither value "1 ", are different on four frames 1 F to 4F basis. In each of the dither mask patterns, the position of " 1 " can vary in various manners according to a designer, if needed. The positions of on-cells corresponding to the dither value " 1 " can be controlled spatially and temporally according to these dither mask patterns. Furthermore, as the position of the dither value " 1 " in the dither mask patterns is different on a gray scale and frame basis, dithering noise such as grating noise, which is caused by the repetition of constant dither mask patterns, can be reduced. The dither mask table 54 in which these dither mask patterns are stored receives some of lower bits of the pixel data received from the confined error diffusion unit 40, e.g., 3 bits of 8-bit pixel data. The dither mask table 54 selects a dither mask pattern of a gray scale that corresponds to the received lower 3 bits from the dither mask patterns as shown in FIG. 8. Then, the dither mask table 54 selects a dither value D2, which corresponds to a frame and the position of a cell, which are indicated by the dither mask control unit 52, from the dither mask patterns of the selected gray scale, and then outputs the selected dither value D2 to the adder 56. For this, the dither mask control unit 52 counts the vertical sync signal V, which is received from an external controller (not shown), to indicate a corresponding frame of the four frames 1 F to 4F, and counts the horizontal sync signal H and the pixel clock signal P to indicate a horizontal line and a vertical line within the corresponding frame, i.e., the position of a cell. In this case, the dither mask control unit 52 controls the dither mask table 54 using the counted signal of the vertical sync signal V, so that the dither mask table 54 selects a dither mask pattern of a corresponding gray scale while toggling the first to fourth frames 1 F to F4. Furthermore, the dither mask control unit 52 controls the number of frames, which are toggled in the dither mask table 54, according to a gray scale of received pixel data. In the concrete, the dither mask control unit 52 compares pixel data that is received from the confined error diffusion unit 40 with a predetermined reference value to determine whether the received pixel data is low gray scale data or high gray scale data. In this time, if it is determined that the received pixel data is the high gray scale data, the dither mask control unit 52 controls the dither mask table 54 to select the dither mask pattern while toggling three frames or four frames 1 F to 4F, as described above. If it is determined that the received pixel data is the low gray scale data, the dither mask control unit 52 controls the dither mask table 54 to select the dither mask pattern while toggling two frames of the four frames 1 F to 4F. Accordingly, if the low gray scale pixel data is consistently displayed during a plurality of frames, it is possible to prevent a flicker phenomenon that is generated due to different dither mask patterns on a frame basis. The adder 56 adds the dither value D2, which is received from the dither mask table 54, to data of upper 5 bits except for lower 3 bits among the pixel data, which is received from the confined error diffusion unit 40, as a carry signal, and thus supplies the corrected 5-bit pixel data to the sub-field mapping unit 34. As such, according to the method and apparatus for processing the video data in the PDP in accordance with the present invention, pixel data, which is expanded from initial 8 bits to 16 bits through the inverse gamma correction operation, is reduced to 5-bit pixel data through the confined error diffusion operation of the confined error diffusion unit 40 and the dithering correction operation of the dithering unit 50. Therefore, nine or more basic gray scales LO to L9, as shown in FIGS. 1 0 and 1 1 , can be represented using the 5-bit pixel data. Furthermore, according to the method and apparatus for processing the video data in the PDP in accordance with the present invention, as shown in FIG. 1 0, the gray scales between the nine or more basic gray scales L0 to L9 are subdivided through the dithering correction using the dither mask patterns as shown in FIG. 8. Thus, the number of gray scales that can be represented increases. This is made possible through a combination of data "1 ", which are variously distributed spatially and temporally, like the dither mask patterns shown in FIG. 8. Moreover, according to the method and apparatus for processing the video data in the PDP in accordance with the present invention, between-gray scales, which are subdivided through the dithering correction operation, are further subdivided through confined error diffusion correction of the confined error diffusion unit 40. It is thus possible to further increase the number of gray scales, which can be represented. According to the method and apparatus for processing the video data in the PDP in accordance with the present invention, 8-bit pixel data is reduced to 5-bit pixel data to represent nine or more basic gray scales LO to L9, as illustrated in a brightness characteristic graph of FIG. 1 1 , and gray scales subdivided between the basic gray scales are represented through the confined error diffusion operation and the dithering operation. Accordingly, since an address time can be sufficiently secured due to a reduction in the number of sub-fields, a PDP can be driven in a single scan mode, and linear brightness can be implemented, as shown in FIG. 1 1 . It is thus possible to minimize contour noise due to a difference in light emission patterns.

Claims

What Is Claimed Is:
1 . A method of processing video data in a plasma display panel in which the number of bits of the video data is reduced through an error diffusion method and a dithering method, comprising the steps of: performing a confined error diffusion process on inputted video data within the range of dither mask patterns of an upper gray scale; and dithering the confined error-diffused video data using a plurality of dither mask patterns that are separated on a gray scale and frame basis.
2. The method as claimed in claim 1 , wherein the inputted video data is inverse gamma-corrected video data.
3. The method as claimed in claim 1 , wherein the step of performing the confined error diffusion process comprises the steps of: generating a first carry signal by adding error diffusion coefficients, which are calculated by assigning different weights to data of pixels adjacent to some of lower bits of the inputted video data; generating a second carry signal by comparing the first carry signal with a dither value at a position corresponding to the inputted video data in the dither mask patterns of the upper gray scale; and outputting the second carry signal which is added to the remaining upper bits of the inputted video data.
4. The method as claimed in claim 3, wherein the step of generating the first carry signal further comprises the step of adding random error diffusion coefficients to the calculated error diffusion coefficients.
5. The method as claimed in claim 3, wherein the dither mask patterns of the upper gray scale are selected from dither mask patterns corresponding to a higher gray scale than a gray scale corresponding to some of bits of the inputted video data in a plurality of dither mask patterns that are previously stored.
6. The method as claimed in claim 3, wherein the step of generating the second carry signal comprises the step of performing an AND operation on the first carry signal and the selected dither value.
7. The method as claimed in claim 1 , wherein the dithering step comprises the steps of: selecting dither mask patterns of a corresponding gray scale from the plurality of the dither mask patterns by using some of lower bits of the confined error-diffused video data; selecting a dither value at a position corresponding to the confined error- diffused video data from the selected dither mask patterns; and adding the selected dither value to the remaining upper bits of the confined error-diffused video data.
8. The method as claimed in claim 7, wherein the step of selecting the dither value comprises the step of counting a vertical sync signal, a horizontal sync signal and a pixel clock signal, respectively, which are received externally, and then selecting a position corresponding to the confined error-diffused video data using the counted signals.
9. The method as claimed in claim 8, wherein the step of selecting the dither value comprises the step of selecting the dither value while toggling dither mask patterns of a corresponding gray scale, which are different on a frame basis, according to the count signal for the vertical sync signal.
1 0. The method as claimed in claim 9, wherein the step of selecting the dither value comprises the step of comparing the confined error-diffused video data with a predetermined reference value, and if the confined error-diffused video data is smaller than the predetermined reference value, reducing the number of the toggled frames.
1 1 . An apparatus for processing video data in a plasma display panel in which the number of bits of the video data is reduced through an error diffusion method and a dithering method, comprising: a confined error diffusion unit for performing a confined error diffusion process on inputted video data within the range of dither mask patterns of an upper gray scale; and a dithering unit for dithering the confined error-diffused video data using a plurality of dither mask patterns that are separated on a gray scale and frame basis.
1 2. The apparatus as claimed in claim 1 1 , further comprising an inverse gamma correction unit for performing an inverse gamma correction process on the inputted video data.
13. The apparatus as claimed in claim 1 1 , wherein the confined error diffusion unit comprises: a dither mask select unit for selecting a dither value at a position corresponding to the inputted video data from dither mask patterns of an upper gray scale; and an error diffusion filter for generating a second carry signal by comparing a first carry signal, which is generated by performing an error diffusion process on the inputted video data, with the dither value, and outputting confined error- diffused video data by adding the second carry signal to the inputted video data.
14. The apparatus as claimed in claim 1 3, wherein the dither mask select unit selects any one of the dither mask patterns corresponding to a gray scale, which is higher than a gray scale corresponding to some of bits of the inputted video data, from the plurality of the dither mask patterns, which are stored in the dithering unit as the dither value mask patterns of the upper gray scale.
1 5. The apparatus as claimed in claim 1 3, wherein the error diffusion filter generates a first carry signal by adding error diffusion coefficients, which are calculated by assigning different weights to data of pixels adjacent to some of lower bits of the inputted video data, generates a second carry signal by comparing the first carry signal with a dither value at a position corresponding to the inputted video data in the dither mask patterns of the upper gray scale, and adds the second carry signal to the remaining upper bits of the inputted video data.
1 6. The apparatus as claimed in claim 1 3, wherein the error diffusion filter generates the second carry signal by performing an AND operation on the first carry signal and the selected dither value.
1 7. The apparatus as claimed in claim 1 3, wherein the confined error diffusion unit further comprises a random error diffusion coefficient generator that generates random error diffusion coefficients that will be additionally added to the calculated error diffusion coefficients.
1 8. The apparatus as claimed in claim 1 1 , wherein the dithering unit comprises: a dither mask table for storing the plurality of the dither mask patterns, and selecting a dither value corresponding to the confined error-diffused video data from the stored dither mask patterns; a mask control unit for controlling the dither mask table to indicate a position corresponding to the confined error-diffused video data; and an adder for adding the dither value to the confined error-diffused video data.
1 9. The apparatus as claimed in claim 18, wherein the dither mask table selects dither mask patterns of a corresponding gray scale from the plurality of the dither mask patterns by using some of lower bits of the confined error-diffused video data, and selects a dither value at a position corresponding to the confined error-diffused video data from the selected dither mask patterns under the control of the mask control unit.
20. The apparatus as claimed in claim 1 8, wherein the adder adds the selected dither value to the remaining upper bits of the confined error-diffused video data.
21 . The apparatus as claimed in claim 1 8, wherein the mask control unit counts a vertical sync signal, a horizontal sync signal and a pixel clock signal, respectively, which are received externally, and then indicates a position corresponding to the confined error-diffused video data using the counted signals.
22. The apparatus as claimed in claim 21 , wherein the mask control unit controls the dither mask table to select the dither value while toggling dither mask patterns of a corresponding gray scale, which are different on a frame basis, according to the counted signal of the vertical sync signal.
23. The apparatus as claimed in claim 22, wherein the mask control unit compares the confined error-diffused video data with a predetermined reference value, and if the confined error-diffused video data is smaller than the predetermined reference value, reduces the number of the toggled frames.
PCT/KR2004/003245 2003-12-10 2004-12-10 Method and apparatus of processing video data for plasma display panel Ceased WO2005057540A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
KR10-2003-0089890A KR100505989B1 (en) 2003-12-10 2003-12-10 Method And Apparatus of Processing Video Data For Plasma Display Panel
KR10-2003-0089890 2003-12-10

Publications (1)

Publication Number Publication Date
WO2005057540A1 true WO2005057540A1 (en) 2005-06-23

Family

ID=34675733

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/KR2004/003245 Ceased WO2005057540A1 (en) 2003-12-10 2004-12-10 Method and apparatus of processing video data for plasma display panel

Country Status (2)

Country Link
KR (1) KR100505989B1 (en)
WO (1) WO2005057540A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009074054A1 (en) * 2007-11-23 2009-06-18 Sichuan Coc Display Devices Co., Ltd. A method and apparatus for reducing image dynamic false contour in ac plasma display
CN101777303A (en) * 2010-03-17 2010-07-14 四川虹欧显示器件有限公司 Method and device for reducing dynamic false contour of plasma display screen

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100539166B1 (en) * 2004-05-31 2005-12-27 엘지전자 주식회사 Device and Method for Driving Plasma Display Panel
KR100593069B1 (en) * 2004-11-12 2006-06-26 엘지전자 주식회사 Image processing apparatus and method of plasma display panel

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH08286634A (en) * 1995-04-17 1996-11-01 Fujitsu Ltd Halftone display method
KR20030006074A (en) * 2001-07-11 2003-01-23 김춘우 Dithering Method for Gradation Expression for Plasma Display Panel and System thereof
JP2003198842A (en) * 2001-12-26 2003-07-11 Matsushita Electric Ind Co Ltd Image processing device
KR20030086854A (en) * 2002-05-07 2003-11-12 주식회사 대우일렉트로닉스 Apparatus for dithering by using random dither pattern

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH08286634A (en) * 1995-04-17 1996-11-01 Fujitsu Ltd Halftone display method
KR20030006074A (en) * 2001-07-11 2003-01-23 김춘우 Dithering Method for Gradation Expression for Plasma Display Panel and System thereof
JP2003198842A (en) * 2001-12-26 2003-07-11 Matsushita Electric Ind Co Ltd Image processing device
KR20030086854A (en) * 2002-05-07 2003-11-12 주식회사 대우일렉트로닉스 Apparatus for dithering by using random dither pattern

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009074054A1 (en) * 2007-11-23 2009-06-18 Sichuan Coc Display Devices Co., Ltd. A method and apparatus for reducing image dynamic false contour in ac plasma display
US8670005B2 (en) 2007-11-23 2014-03-11 Sichuan Coc Display Devices Co., Ltd. Method and system for reducing dynamic false contour in the image of an alternating current plasma display
CN101777303A (en) * 2010-03-17 2010-07-14 四川虹欧显示器件有限公司 Method and device for reducing dynamic false contour of plasma display screen

Also Published As

Publication number Publication date
KR100505989B1 (en) 2005-08-03
KR20050057739A (en) 2005-06-16

Similar Documents

Publication Publication Date Title
EP1536400B1 (en) Method for processing a gray level in a plasma display panel and apparatus using the same
AU785352B2 (en) Method and apparatus for processing video pictures
KR100499102B1 (en) Apparatus and Method of Driving Plasma Display Panel
EP1548696B1 (en) Method and apparatus for driving plasma display panel
KR100512104B1 (en) Method for processing a gray scale in a display device and apparatus using the same
JP4925576B2 (en) Apparatus and method for driving plasma display panel
US7256794B2 (en) Method and apparatus for processing video data of display device
EP1542199A2 (en) Method and apparatus for driving plasma display panel
WO2005057540A1 (en) Method and apparatus of processing video data for plasma display panel
KR100570968B1 (en) Method and apparatus for processing video data of plasma display panel
JP4160575B2 (en) Plasma display device and driving method thereof
KR100512105B1 (en) Method for processing a gray scale in a display device and apparatus using the same
KR100531484B1 (en) Method and Apparatus for Driving Plasma Display Panel
KR20050101442A (en) Image processing apparatus for plasma display panel
KR20060088671A (en) Apparatus and method for processing video data of plasma display panel
KR20060083046A (en) Driving apparatus and method of plasma display panel

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BW BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE EG ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NA NI NO NZ OM PG PH PL PT RO RU SC SD SE SG SK SL SY TJ TM TN TR TT TZ UA UG US UZ VC VN YU ZA ZM ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): GM KE LS MW MZ NA SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LT LU MC NL PL PT RO SE SI SK TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
122 Ep: pct application non-entry in european phase