EP1619651A1 - Method and device for processing video data by combining error diffusion and dithering - Google Patents

Method and device for processing video data by combining error diffusion and dithering Download PDF

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Publication number
EP1619651A1
EP1619651A1 EP04291878A EP04291878A EP1619651A1 EP 1619651 A1 EP1619651 A1 EP 1619651A1 EP 04291878 A EP04291878 A EP 04291878A EP 04291878 A EP04291878 A EP 04291878A EP 1619651 A1 EP1619651 A1 EP 1619651A1
Authority
EP
European Patent Office
Prior art keywords
pixel
dithering
error
cell
error diffusion
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.)
Withdrawn
Application number
EP04291878A
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German (de)
English (en)
French (fr)
Inventor
Sebastien Weitbruch
Cedric Thebault
Carlos Correa
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.)
Deutsche Thomson Brandt GmbH
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Deutsche Thomson Brandt GmbH
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 Deutsche Thomson Brandt GmbH filed Critical Deutsche Thomson Brandt GmbH
Priority to EP04291878A priority Critical patent/EP1619651A1/en
Priority to EP20050106222 priority patent/EP1619649B1/en
Priority to KR1020050065710A priority patent/KR20060053933A/ko
Priority to MXPA05007706A priority patent/MXPA05007706A/es
Priority to US11/186,471 priority patent/US7738719B2/en
Priority to JP2005212923A priority patent/JP5074675B2/ja
Priority to CNB2005100849052A priority patent/CN100573632C/zh
Publication of EP1619651A1 publication Critical patent/EP1619651A1/en
Withdrawn legal-status Critical Current

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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
    • G09G3/2059—Display of intermediate tones using error diffusion
    • G09G3/2062—Display of intermediate tones using error diffusion using error diffusion in time
    • G09G3/2066—Display of intermediate tones using error diffusion using error diffusion in time with error diffusion in both space and time
    • 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
    • G09G3/2062—Display of intermediate tones using error diffusion using error diffusion in time
    • 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
    • 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
    • G09G3/2051—Display of intermediate tones using dithering with use of a spatial dither pattern
    • 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 for processing video data for display on a display device having a plurality of luminous elements corresponding to the pixels of a picture, wherein the time of a video frame or field is divided into a plurality of sub-fields during which the luminous elements can be activated for light emission in small pulses corresponding to a sub-field code word of n bits used for encoding the p possible video levels lighting a pixel, comprising the steps of: performing an error diffusion and another dithering for reducing a quantization error. Furthermore, the present invention relates to a corresponding device for processing video data.
  • a PDP utilizes a matrix array of discharge cells, which can only be "ON”, or “OFF”. Also unlike a CRT or LCD in which grey levels are expressed by analogue control of the light emission, a PDP controls the grey level by modulating the number of light pulses per frame (sustain pulses). This time-modulation will be integrated by the eye over a period corresponding to the eye time response. Since the amplitude video is portrayed by the number of light pulses, occurring at a given frequency, more amplitude means more light pulses and thus more "ON" time. For this reason, this kind of modulation is also known as PWM, pulse width modulation. This PWM is responsible for one of the PDP image quality problems: the poor grey scale portrayal quality, especially in the darker regions of the picture.
  • a dithering signal is added to a processed video signal, before truncation to the final video grey scale amplitude resolution.
  • Dithering is a well-known technique from the technical literature, used to reduce the effects of quantization noise due to a reduced number of displayed resolution bits. Dithering, by adding artificial levels in-between, improves grey scale portrayal, but adds high frequency low amplitude dithering noise, perceptible to the human viewer only at a small viewing distance.
  • plasma uses PWM (pulse width modulation) to generate the different shades of grey. Contrarily to CRTs where luminance is approximately quadratic to applied cathode voltage, luminance is linear to the number of discharge pulses. Therefore an approximately digital quadratic degamma function has to be applied to video before the PWM.
  • PWM pulse width modulation
  • the output number of quantization bits is smaller than the input number, in particular values smaller than 16 (when working with 8 bit for video input) are all mapped to value 0 (this corresponds to four bit resolution which is actually unacceptable for video).
  • a 8-bit display like a PDP will not be able to render the fractional part. Therefore, if nothing special is done, the low input levels are all mapped to 0 and so on.
  • dithering is a known technique for avoiding losing amplitude resolution bits to truncation. It only works if the resolution is available before truncation, which is the present case (if more bits are used for degamma). Dithering can in principle bring back as many bits as those lost by truncation. However dithering noise frequency decreases, and therefore becomes more noticeable, with the number of dithering bits.
  • 1 bit of dithering corresponds to multiply the number of available output levels by 2, 2 bits of dithering multiply by 4, and 3 bits of dithering multiply by 8 the number of output levels.
  • Cell-based dithering adds a dithering pattern that is defined for every cell of the panel and not for every pixel (3 cells) of this panel.
  • a panel pixel is composed of three cells: red, green and blue. This has the advantage of rendering the dithering noise finer and thus less noticeable to the human viewer. The difference can directly be seen in Fig. 1.
  • the multi-mask dithering represents an improved version of the cell-based dithering by using different kinds of dithering functions depending of the fractional part to be rendered. For instance, for 3bit dithering able to render 8 different fractional parts of the value x, 8 different masks will be used (cf.EP 1 262 947) as described below:
  • error diffusion is a neighbourhood operation that quantizes the current pixel signal for example by keeping the integer part of the signal value) and then transfers the quantization error (fractional part) onto future pixels.
  • Floyd and Steinberg An adaptive algorithm for spatial greyscale
  • y [ h ] int(x [ n ] +x e [ n ] )
  • the error diffusion process itself consists of three steps. First, a modified input is formed as the sum of the original input value and the diffused past errors (located above and left of the current pixel). In the second step, this modified error is rounded to yield the output. As the last step, the quantization error (rest of fractional part) is calculated as the difference between the modified input and the final output. Then, this quantization error will be spread to the neighbouring pixels by weighting it with a coefficient that can be chosen in various ways.
  • Fig. 2 illustrates this principle.
  • the value of the current pixel is 4.5. Then, this value is rounded to 4 generating an error of 0.5.
  • This error will be diffused on three neighboring pixels using three different coefficients (0.5 for the right pixel, 0.3 for the bottom right and 0.2 for the bottom one). Normally, the coefficients are chosen in order to keep the energy constant (sum of coefficient is 1). This is mandatory to keep a good stability in the picture.
  • the main disadvantage of the concept is its dependency from the picture content. Indeed the spread error depends on the value of the current pixel and its effect is only visible on its neighbors and is thus picture dependent. Moreover, the rendition of very low levels is based on some spread pixels far from each other since the spread error is too small to have rapid effect. Finally the effect is more a noise on a low level than a real visible level.
  • a combination of error diffusion and multi-mask dithering might help to render more bits of fractional part if one can keep the major advantages of both concepts: quite invisible dithering pattern with more bits (8 bits will be studied as example in the following parts of this document).
  • 8.8 bits means 8-bit integer and 8-bit fractional part. Since the 8 bits of the fractional part shall be handled differently, they will be decomposed in the 3 MSBs followed by 5 LSBs described as "3.5". Finally, the 16-bits of information are described under the form 8.3.5 bits.
  • the 8 bits of video information are forwarded to a degamma block 1.
  • This block 1 will perform the quadratic degamma function with 16 bits resolution in order to deliver 8.3.5 bits of information.
  • the 5 lowest bits will be diffused in block 2 following a standard error diffusion principle as explained before. Therefore, after this block 2, there are only 8.3 bits of information (5 LSBs being diffused before, symbolized by adder 3).
  • the 3bits of the fractional part are used to select the appropriate mask 4 from the multi-mask dithering function 4, 5, which will be applied to the picture depending on the frame number, pixel position and colour (R, G or B).
  • the output value of the mask is either 000 (corresponding to value "0") or 111 (corresponding to value "1") that is added to the current 8.3 bit value.
  • a simple truncation 6 will deliver a standard 8-bit integer to the display 7.
  • this object is solved by a method for processing video data for display on a display device having a plurality of luminous elements corresponding to the pixels of a picture, wherein the time of a video frame or field is divided into a plurality of sub-fields during which the luminous elements can be activated for light emission in small pulses corresponding to a sub-field code word of n bits used for encoding the p possible video levels lighting a pixel, comprising the steps of:
  • the error diffusion is applied under the control of the cell-based pixel-based or multi-mask dithering.
  • a annoying artefacts can be avoided.
  • the error diffusion for a pixel or a cell is performed if the value of dithering is "1". Since the values of dithering usually are "0" or "1" these values can also be used as switching bits.
  • the code words should be processed with more than n bits, so that fractional parts of code words can be formed, and the error diffusion is applicable on all bits of a fractional part. However, best results are obtained, if the result of a cell-based, pixel-based or multi-mask dithering is used as switching parameter for switching on and off the error diffusion.
  • the highest bit or a couple of the highest bits of a fractional part may be used for determining the value of the cell-based, pixel-based or multi-mask dithering.
  • the error diffusion for smaller quantization errors may be accumulated for one cell or one pixel.
  • error diffusion can be performed depending on the content of the picture. If an error is not diffused it may be stored for a future pixel.
  • the error to be added to a pixel or a cell by error diffusion may be limited to a maximum error.
  • a maximum error is 1. This limitation guarantees that the error does not increase unduly.
  • the main issue of combining the error diffusion with the multi-mask/cell-based dithering should be to achieve a rendition of more bits of fractional part while keeping the advantage of a structure of dithering similar to the multi-mask. According to the present invention this is achieved by a diffusion of all 8 bits of fractional part but the error will only be applied on cells having their multi-mask value at 1. In order to determine the value of the multi-mask, the three highest bits of the fractional part will be chosen. This concept is illustrated in Fig. 4.
  • the input 8 bits of video information are forwarded to the degamma block 1.
  • This block 1 will perform the quadratic function with 16 bits resolution in order to deliver 8.3.5 bits of information.
  • the complete information is input into an error diffusion block 2 thereby passing an adder 3'.
  • the 3 MSBs of the fractional part of the output from the degamma block 1 are used to define the output of the multi-mask dithering 4', this being 1 or 0.
  • a swith 8 is controlled by the output of the multi-mask block 4'. In case of 1, the error diffused to this pixel is accepted and added by adder 3' to the pixel before going to the error diffusion block 2.
  • the diffused error is refused, and will be re-injected via swith 8 inside the error diffusion block 2.
  • the error diffusion will only be applied in a multi-mask matrix manner keeping all advantages of this concept.
  • the value applied in a multi-mask manner is 8-bit fractional and follows the error diffusion principle. As illustrated in Fig. 4 the error diffused can be up to 1.8 bits since the error can be accumulated on a higher number of iterations (if often rejected).
  • FIG. 5 An improved embodiment of the invention is shown in Fig. 5. Since the error diffused to one pixel can be, depending on the multi-mask value, re-injected inside the error diffusion block 2, it is easy to understand that the error can increase a lot. Therefore, an improvement of the concept will be to limit the error that can be added to the current pixel to a maximum by a limiter 9. The rest being re-injected again inside the error diffusion block as shown in Figure 5.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Control Of Indicators Other Than Cathode Ray Tubes (AREA)
  • Transforming Electric Information Into Light Information (AREA)
EP04291878A 2004-07-23 2004-07-23 Method and device for processing video data by combining error diffusion and dithering Withdrawn EP1619651A1 (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
EP04291878A EP1619651A1 (en) 2004-07-23 2004-07-23 Method and device for processing video data by combining error diffusion and dithering
EP20050106222 EP1619649B1 (en) 2004-07-23 2005-07-07 Method and device for processing video data by combining error diffusion and another dithering
KR1020050065710A KR20060053933A (ko) 2004-07-23 2005-07-20 에러 확산과 또 다른 디더딩을 결합함으로써 비디오데이터를 처리하는 방법 및 장치
MXPA05007706A MXPA05007706A (es) 2004-07-23 2005-07-20 Metodo y dispositivo para procesamiento de datos de video al combinar difusion de error y otras oscilaciones.
US11/186,471 US7738719B2 (en) 2004-07-23 2005-07-21 Method and device for processing video data by combining error diffusion and another dithering
JP2005212923A JP5074675B2 (ja) 2004-07-23 2005-07-22 誤差拡散及び他のディザリングの組み合わせによる映像データ処理の方法及び装置
CNB2005100849052A CN100573632C (zh) 2004-07-23 2005-07-25 通过组合误差扩散与另一抖动处理视频数据的方法和设备

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP04291878A EP1619651A1 (en) 2004-07-23 2004-07-23 Method and device for processing video data by combining error diffusion and dithering

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EP1619651A1 true EP1619651A1 (en) 2006-01-25

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120114039A1 (en) * 2010-11-09 2012-05-10 Sony Computer Entertainment Inc. Video coding methods and apparatus

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4549418B2 (ja) * 2008-03-04 2010-09-22 シャープ株式会社 画像処理装置、画像処理方法、画像形成装置、並びに、プログラム、記録媒体
CN105208363B (zh) * 2015-09-17 2018-02-09 暴风集团股份有限公司 对颜色空间转换中抖色调整量化补偿的方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6069609A (en) * 1995-04-17 2000-05-30 Fujitsu Limited Image processor using both dither and error diffusion to produce halftone images with less flicker and patterns
EP1262947A1 (en) * 2001-06-01 2002-12-04 Thomson Licensing S.A. Method and apparatus for processing video picture data for a display device

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6069609A (en) * 1995-04-17 2000-05-30 Fujitsu Limited Image processor using both dither and error diffusion to produce halftone images with less flicker and patterns
EP1262947A1 (en) * 2001-06-01 2002-12-04 Thomson Licensing S.A. Method and apparatus for processing video picture data for a display device

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
WEITBRUCH S ET AL: "NEW METACODE CODING CONCEPT FOR IMPROVING PDP GRAY-SCALE QUALITY", JOURNAL OF THE SOCIETY FOR INFORMATION DISPLAY, SOCIETY FOR INFORMATION DISPLAY, SAN JOSE, US, vol. 11, no. 3, 2003, pages 485 - 491, XP001180890, ISSN: 1071-0922 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120114039A1 (en) * 2010-11-09 2012-05-10 Sony Computer Entertainment Inc. Video coding methods and apparatus

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Publication number Publication date
CN100573632C (zh) 2009-12-23
CN1725278A (zh) 2006-01-25

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