EP0987675A1 - Vorrichtung und Verfahren zur Video-Bildbearbeitung, insbesondere zur Kompensation des Falschkontureneffekts - Google Patents

Vorrichtung und Verfahren zur Video-Bildbearbeitung, insbesondere zur Kompensation des Falschkontureneffekts Download PDF

Info

Publication number
EP0987675A1
EP0987675A1 EP99117531A EP99117531A EP0987675A1 EP 0987675 A1 EP0987675 A1 EP 0987675A1 EP 99117531 A EP99117531 A EP 99117531A EP 99117531 A EP99117531 A EP 99117531A EP 0987675 A1 EP0987675 A1 EP 0987675A1
Authority
EP
European Patent Office
Prior art keywords
sub
pixels
code word
field
digital code
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Withdrawn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
EP99117531A
Other languages
English (en)
French (fr)
Inventor
Carlos Correa
Sebastian Weitbruch
Gangolf Hirtz
Didier Doyen
Jean Claude Chevet
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
Original Assignee
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
Priority claimed from EP98121334A external-priority patent/EP0978816B1/de
Application filed by Deutsche Thomson Brandt GmbH filed Critical Deutsche Thomson Brandt GmbH
Priority to EP99117531A priority Critical patent/EP0987675A1/de
Publication of EP0987675A1 publication Critical patent/EP0987675A1/de
Withdrawn legal-status Critical Current

Links

Images

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
    • G09G3/2018—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
    • G09G3/2033—Display of intermediate tones by time modulation using two or more time intervals using sub-frames with splitting one or more sub-frames corresponding to the most significant bits into two or more 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
    • G09G3/2018—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
    • G09G3/2029—Display of intermediate tones by time modulation using two or more time intervals using sub-frames the sub-frames having non-binary weights
    • 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
    • G09G2320/0266—Reduction of sub-frame artefacts
    • 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
    • G09G2320/0285—Improving the quality of display appearance using tables for spatial correction of display data
    • 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
    • G09G2320/10—Special adaptations of display systems for operation with variable images
    • G09G2320/106—Determination of movement vectors or equivalent parameters within the image
    • 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

Definitions

  • the invention relates to a method and apparatus for processing video pictures, especially for false contour effect compensation. More specifically the invention is closely related to a kind of video processing for improving the picture quality of pictures which are displayed on matrix displays like plasma display panels (PDP) or display devices with digital micro mirror arrays (DMD).
  • PDP plasma display panels
  • DMD digital micro mirror arrays
  • plasma display panels are known for many years, plasma displays are encountering a growing interest from TV manufacturers. Indeed, this technology now makes it possible to achieve flat color panels of large size and with limited depths without any viewing angle constraints.
  • the size of the displays may be much larger than the classical CRT picture tubes would have ever been allowed.
  • the invention deals with a specific new artefact, which is called "dynamic false contour effect" since it corresponds to disturbances of gray levels and colors in the form of an apparition of colored edges in the picture when an observation point on the matrix screen moves.
  • This kind of artefact is enhanced when the image has a smooth gradation like when the skin of a person is being displayed (e. g. displaying of a face or an arm, etc.).
  • the same problem occurs on static images when observers are shaking their heads and that leads to the conclusion that such a failure depends on the human visual perception and happens on the retina of the eye.
  • Pulse equalization technique This technique is described e.g. in Euro Display 1996, "An Equalising Pulse Technique for Improving the Gray Scale Capability of Plasma Displays", K. Toda et al., pages 39 to 42.
  • This technique is a more complex one. It utilizes equalizing pulses which are added or separated from the TV signal when disturbances of gray scales are foreseen.
  • equalizing pulses which are added or separated from the TV signal when disturbances of gray scales are foreseen.
  • different pulses for each possible speed are needed. That leads to the need of a big memory storing a number of big look-up tables (LUT) for each speed and there is a need of a motion estimator.
  • the general idea of the invention is that the correction of pixel values is made not on amplitude values only without consideration of the position of the sub-fields which are inserted or omitted but on sub-field level.
  • the sub-fields for correction are positioned at the best possible location in the frame period for false contour effect compensation.
  • a correction performed on subfield level allows directly to insert or to remove subfields on the position (time position within the frame) where too much or not enough light impulses are available. This way it's possible to compensate directly the failures where they occur.
  • the apparatus calculates motion vectors for blocks of pixels of the video frames. It also comprises means for determining critical pixel value transitions which are moving. For given motion vectors and critical pixel value transitions look-up tables are provided in which the corrected digital code words are stored which are to be used for a good false contour effect compensation.
  • Fig. 1 The artefact due to the false contour effect is shown in Fig. 1.
  • two dark lines On the arm of the displayed woman are shown two dark lines, which e. g. are caused by this false contour effect. Also in the face of the woman such dark lines occur on the right side.
  • a plasma display panel utilizes a matrix array of discharge cells which could only be switched ON or OFF. Also unlike a CRT or LCD in which gray levels are expressed by analog control of the light emission, in a PDP the gray level is controlled by modulating the number of light pulses per frame. This time-modulation will be integrated by the eye over a period corresponding to the eye time response. When an observation point (eye focus area) on the PDP screen moves, the eye will follow this movement. Consequently, it will no more integrate the light from the same cell over a frame period (static integration) but it will integrate information coming from different cells located on the movement trajectory. Thus it will mix all the light pulses during this movement which leads to a faulty signal information. This effect will now be explained in more detail below.
  • the frame period will be divided in 8 lighting periods which are also very often referred to sub-fields, each one corresponding to one of the 8 bits.
  • the above-mentioned sub-field organization is shown in Fig. 2.
  • the light emission pattern according to the sub-field organization introduces new categories of image quality degradation corresponding to disturbances of gray levels and colors.
  • these disturbances are defined as so-called dynamic false contour effect since the fact that it corresponds to the appearance of colored edges in the picture when an observation point on the PDP screen moves.
  • the observer has the impression of a strong contour appearing on a homogeneous area like displayed skin.
  • the degradation is enhanced when the image has a smooth gradation and also when the light emission period exceeds several milliseconds. So, in dark scenes the effect is not so disturbing as in scenes with average gray level (e.g. luminance values from 32 to 223).
  • Fig. 3 shows a darker shaded area corresponding to the luminance level 128 and a lighter shaded area corresponding to the luminance area level 127.
  • the sub-field organization, shown in Fig. 2 is used for building the luminance levels 128 and 127 as it is depicted on the right side of Fig. 3.
  • the three parallel lines in Fig. 3 indicate the direction in which the eye is following the movement.
  • the two outer lines show the area borders where a faulty signal will be perceived.
  • Fig. 4 there is shown a curve which illustrates the behavior of the eye cells during observing the moving picture depicted in Fig. 3. The eye cells having a good distance from the horizontal transition will integrate enough light from the corresponding pixels. Only the eye cells which are near the transition will not be able to integrate a lot of light from the same pixels.
  • a new sub-field organization which has more sub-fields and above all has more sub-fields with the same weight. This will already reduce the contouring effect and improve the situation. Furthermore, it allows for the inventive correction method which will be explained afterwards.
  • Fig. 5 two examples of new coding schemes are shown. The choice of the optimal one has to be made depending on the plasma technology. In the first example there are ten sub-fields used wherein there are four sub-fields having lighting periods with a relative duration of 48/256. In the second example there are twelve sub-fields and there are seven sub-fields having the relative duration of 32/256. Please note that the frame period has a relative duration of 256/256.
  • Fig. 6 the result of the new sub-field organization according to the second example of Fig. 5 is shown in case of the 128/127 horizontal transition moving at a speed of five pixels per frame. Now, the chance that the corresponding eye cells will integrate more similar amounts of lighting periods is increased. This is illustrated by the eye-stimuli integration curve at the bottom of Fig. 6 when compared to the eye-stimuli integration curve at the bottom of Fig. 3.
  • the known false contour correction methods (with equalizing pulses) correct directly the pixel values of the video signal, i.e. correction is done before the sub-field conversion.
  • FIG. 7 An illustration of this method is shown in Fig. 7. From Fig. 7a) it follows that in the middle of the transition the amplitude on the eye retina has a lack of 32 relative amplitude units. This is compensated by simply adding this value to the pixels of the transition, see Fig. 7b). Since the brightness impression on the eye is given by the integration of the light amplitude over a certain time period, such a correction cannot be perfect when the eye moves.
  • the eye stimuli integration curve shown at the bottom of Fig. 8 indicates that the false contour effect is reduced compared to Fig. 6 but still present.
  • a correction value of 32 can have an influence on different timing positions, e.g. SF 9 or SF10.
  • a motion estimator is applied for providing motion vectors of blocks of pixels.
  • the original picture is segmented in blocks, each of which will have a single motion vector assigned.
  • An example of such a decomposition is shown in Fig. 9.
  • Other types of motion-dependent pictures segmentations could be used, since the goal is only to decompose the picture in basic elements having a well-defined motion vector. So all motion estimators can be used for the invention, which are able to subdivide a picture in blocks and to calculate for each block a corresponding motion vector.
  • motion estimators are well-known from, for example 100 Hz up-conversion technique and also from MPEG coding etc., they are well-known in the art and there is no need to describe them in greater detail here.
  • a motion estimator which could be used in this invention, it is referred to WO-A-89/08891. Best to be used are motion estimators which give precisely the direction of the movement and the amplitude of this movement for each block. Since most of the plasma display panels are working on RGB component data, benefit could be achieved when for each RGB component a separate motion estimation is being carried out and these three components are combined so that the efficiency of the motion estimation will be improved.
  • each block can be evaluated for critical transitions.
  • a critical transition is found when two areas of pixels with slightly different pixel values are found.
  • most of the sub-fields of the two pixel value code words are identical except for one sub-field with greater weight and a number of sub-fields with smaller weight (see e.g. Fig. 6).
  • a correction performed on sub-field level according to the invention allows directly to insert or to remove subfields on the position (time position within the frame) where too much or not enough light impulses are available. This way it's possible to compensate directly the failures where they occur.
  • subfields are inserted or removed depending on the transition and the speed of movement. That means that it's directly possible to insert or remove light pulses on positions (in temporal direction) where they are missing or are too much.
  • the main difference to the amplitude based compensation is that with the amplitude based compensation technique it is not possible to determine the time where the additional light pulses are best to be inserted or removed.
  • the subfield-based compensation technique is depicted with an example.
  • the additional subfields are shown with small black boxes.
  • the correction depicted in Fig. 10 is an example for a good false contour effect compensation for this transition and movement.
  • the additional subfields are shown with small black boxes, generate light pulses exactly in the time period where they are needed. Within the area of the parallel lines shown, the eye will perceive light emission pulses of total weight ⁇ 128 when looking along the shown direction. But it is to be noted that the integration of the eye retina is also a function of time distance between the sub-fields.
  • Fig. 11 The video processing block used to compensate the false contour effect is shown in Fig. 11.
  • Reference number 10 denotes the whole block.
  • RGB data is input to this block.
  • a motion estimation and transition detection unit 12 Within this unit the picture is subdivided in blocks and motion vectors are calculated for the blocks. Preferably the subdivision in blocks is made so that all pixels in the blocks have identical pixel values. When the motion vectors are found, critical transitions are searched.
  • look up table memory 13 a number of look up tables 14 are stored.
  • the information regarding motion vector and transition classification serves as an address for the right table. From the information found during transition detection a control signal is generated which controls which entry in the selected look up table is to be output. For the pixels of the transition which are to be corrected new sub-field codes are stored in the look up table and these codes are read out under control of this signal.
  • Another control signal is generated for the control of a demultiplexer 15 at the output of the look up table. This signal is used to switch between the output of the look up table 14 and the output of sub-field code generation unit 16 in which the RGB pixel values of a frame are converted to sub-field codes.
  • Another look up table can be used for this purpose. As a result, at the output of look up table unit 13 the sub-field codes of the frame are supplied to the display unit inclusive the corrected sub-field codes for the critical moving transitions.
  • An alternative embodiment is one without motion estimator.
  • the pixel values of two succeeding frames are compared pixel by pixel and each time, a critical difference is found a corresponding corrected sub-field code is selected in a look up table.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Control Of Gas Discharge Display Tubes (AREA)
  • Control Of Indicators Other Than Cathode Ray Tubes (AREA)
EP99117531A 1998-09-16 1999-09-04 Vorrichtung und Verfahren zur Video-Bildbearbeitung, insbesondere zur Kompensation des Falschkontureneffekts Withdrawn EP0987675A1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP99117531A EP0987675A1 (de) 1998-09-16 1999-09-04 Vorrichtung und Verfahren zur Video-Bildbearbeitung, insbesondere zur Kompensation des Falschkontureneffekts

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
EP98117523 1998-09-16
EP98117523 1998-09-16
EP98121334A EP0978816B1 (de) 1998-08-07 1998-11-10 Verfahren und Vorrichtung zur Videobildbearbeitung, insbesondere zur Kompensation des Falschkontureffekts
EP98121334 1998-11-10
EP99117531A EP0987675A1 (de) 1998-09-16 1999-09-04 Vorrichtung und Verfahren zur Video-Bildbearbeitung, insbesondere zur Kompensation des Falschkontureneffekts

Publications (1)

Publication Number Publication Date
EP0987675A1 true EP0987675A1 (de) 2000-03-22

Family

ID=27239154

Family Applications (1)

Application Number Title Priority Date Filing Date
EP99117531A Withdrawn EP0987675A1 (de) 1998-09-16 1999-09-04 Vorrichtung und Verfahren zur Video-Bildbearbeitung, insbesondere zur Kompensation des Falschkontureneffekts

Country Status (1)

Country Link
EP (1) EP0987675A1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1162571A1 (de) * 2000-06-09 2001-12-12 Deutsche Thomson-Brandt Gmbh Verfahren und Vorrichtung zur Videobildbearbeitung, insbesondere zur Kompensation des Falschkontureffekts

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0720139A2 (de) * 1994-12-27 1996-07-03 Pioneer Electronic Corporation Verfahren zum Korrigieren von Grauskaladaten für ein Steuerungssystem einer selbstleuchtenden Anzeigevorrichtung
EP0822536A2 (de) * 1996-07-29 1998-02-04 Fujitsu Limited Verfahren und Vorrichtung zur Anzeige von Halbtonbildern
EP0840274A1 (de) * 1996-10-29 1998-05-06 Fujitsu Limited Darstellung von Halbtonbildern
EP0847037A1 (de) * 1996-12-06 1998-06-10 Matsushita Electric Industrial Co., Ltd. Video-Anzeigemonitor

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0720139A2 (de) * 1994-12-27 1996-07-03 Pioneer Electronic Corporation Verfahren zum Korrigieren von Grauskaladaten für ein Steuerungssystem einer selbstleuchtenden Anzeigevorrichtung
EP0822536A2 (de) * 1996-07-29 1998-02-04 Fujitsu Limited Verfahren und Vorrichtung zur Anzeige von Halbtonbildern
EP0840274A1 (de) * 1996-10-29 1998-05-06 Fujitsu Limited Darstellung von Halbtonbildern
EP0847037A1 (de) * 1996-12-06 1998-06-10 Matsushita Electric Industrial Co., Ltd. Video-Anzeigemonitor

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
YAMAGUCHI T ET AL: "IMPROVEMENT IN PDP PICTURE QUALITY BY THREE-DIMENSIONAL SCATTERING OF DYNAMIC FALSE CONTOURS", SID INTERNATIONAL SYMPOSIUM. DIGEST OF TECHNICAL PAPERS, SAN DIEGO, MAY 12 - 17, 1996, no. VOL. 27, 12 May 1996 (1996-05-12), SOCIETY FOR INFORMATION DISPLAY, pages 291 - 294, XP002055281 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1162571A1 (de) * 2000-06-09 2001-12-12 Deutsche Thomson-Brandt Gmbh Verfahren und Vorrichtung zur Videobildbearbeitung, insbesondere zur Kompensation des Falschkontureffekts

Similar Documents

Publication Publication Date Title
EP0978816B1 (de) Verfahren und Vorrichtung zur Videobildbearbeitung, insbesondere zur Kompensation des Falschkontureffekts
US6473464B1 (en) Method and apparatus for processing video pictures, especially for false contour effect compensation
US7339632B2 (en) Method and apparatus for processing video pictures improving dynamic false contour effect compensation
US6717558B1 (en) Method for processing video pictures for display on a display device and apparatus for carrying out the method
JP2002372948A (ja) Ｐｄｐの駆動方法および表示装置
US7023450B1 (en) Data processing method and apparatus for a display device
KR100887678B1 (ko) 비디오 화상을 처리하기 위한 방법 및 비디오 화상을처리하기 위한 장치
EP1058229B1 (de) Verfahren und Anordnung zur Verarbeitung von Videosignalen
JPH09258688A (ja) ディスプレイ装置
KR100784945B1 (ko) 비디오 화상을 처리하기 위한 방법 및 장치
EP1162571B1 (de) Verfahren und Vorrichtung zur Videobildbearbeitung zur Kompensation des Falschkontureffekts
EP0980059B1 (de) Verfahren und Vorrichtung zur Bearbeitung von Videobildern, insbesondere zur Kompensation des Falschkontureffekts
EP0987675A1 (de) Vorrichtung und Verfahren zur Video-Bildbearbeitung, insbesondere zur Kompensation des Falschkontureneffekts
MXPA00003934A (en) Method and apparatus for processing video signals for display

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE

AX Request for extension of the european patent

Free format text: AL;LT;LV;MK;RO;SI

17P Request for examination filed

Effective date: 20000801

AKX Designation fees paid

Free format text: AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION HAS BEEN WITHDRAWN

18W Application withdrawn

Withdrawal date: 20020315