Method and apparatus for processing video pictures, in particular in film mode sequences

• US 7,911,545 B2
• Filed: 12/14/2004
• Issued: 03/22/2011
• Est. Priority Date: 12/17/2003
• Status: Expired due to Fees

• Current Assignee: Thomson Licensing (Vantiva SA)
• Original Assignee: Thomson Licensing (Vantiva SA)
• Inventors: Thebault, Cédric, Weitbruch, Sébastien, Doser, Ingo
• Primary Examiner(s): KOSTAK, VICTOR R
• Application Number:
  US10/583,211
• Publication Number:
  US 20070279324A1
• Time in Patent Office: 2,289 Days
• Field of Search: 348/797, 348/441, 348/554, 348/607, 348/687, 348/910, 345/60, 345/63, 345691-693
• US Class Current: 348/797
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 2320/0266 Reduction of sub-frame artefacts
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2320/103 Detection of image changes, e.g. determination of an index representative of the image change
• CPC Class Codes: G09G 3/2029 the sub-frames having non-binary weights
• CPC Class Codes: G09G 3/204 the sub-frames being organized in consecutive sub-frame groups
• CPC Class Codes: G09G 3/28 using luminous gas-discharge panels, e.g. plasma panels
• CPC Class Codes: H04N 7/0112 one of the standards corresponding to a cinematograph film standard
• CPC Class Codes: Y10S 348/91 Flicker reduction

Abstract

The invention relates to a method for processing video pictures, the video pictures consisting of pixels digitally coded, the digital code word determining the length of the time period during which the corresponding pixel of a display is activated, wherein to each bit of a digital code word a certain activation duration called sub-field is assigned, the sum of the duration of the sub-fields according to a given code word determining the length of the time period during which the corresponding pixel is activated, said method comprising the following steps:

• • detecting the video pictures source mode and the parity between pictures,
  • if the source is in film mode, distributing the total number of sub-fields used for two frame raster in three groups of sub-fields and assigning to a value of a pixel a code word that corresponds to the distribution of the active sub-fields period over the three sub-fields groups, and
  • if the source is in camera mode, distributing the total number of sub-fields used for each frame raster in two groups of sub-fields and assigning to a value of a pixel a code word that corresponds to the distribution of the active sub-fields period over the two sub-fields groups.
    The invention is applicable to all kinds of displays based on the principle of duty cycle modulation.

Claims

1. Method for processing video pictures and displaying them on a pulse-width modulation-driven display device, the video pictures consisting of pixels digitally coded, the digital code word determining the length of the time period during which the corresponding pixel of a display is activated, wherein to each bit of a digital code word a certain activation duration called sub-field is assigned, the sum of the duration of the sub-fields according to a given code word determining the length of the time period during which the corresponding pixel is activated, said method comprising the following steps:

detecting the video pictures source mode and the parity between pictures,

if the source is in film mode, distributing the total number of sub-fields used for two frame raster in three groups of sub-fields and assigning to a value of a pixel a code word that corresponds to the distribution of the active sub-fields period over the three sub-fields groups, and

if the source is in camera mode, distributing the total number of sub-fields used for each frame raster in two groups of sub-fields and assigning to a value of a pixel a code word that corresponds to the distribution of the active sub-fields period over the two sub-fields groups.

2. Method according to claim 1, wherein each one of the three groups of sub-fields or each one of the two groups of sub-fields comprises a number of sub-fields equal or different by one.

3. Method according to claim 1, wherein the three groups of sub-fields in film mode and the two groups of sub-fields in camera mode have identical structure at least in terms of the most significant sub-fields.

4. Method according to claim 1, wherein the three groups of sub-fields have identical structure at least in terms of the least significant sub-fields.

5. Method according to claim 1, wherein the detection of the video pictures source modes and the parity between pictures is done by analysing the intra field motion.

6. Method according to claim 1, wherein the change of coding from the coding used in camera mode to the coding used in film mode is made at the next frame following the detection of a change between the source type.

7. Method according to claim 1, wherein the change of coding from the coding used in film mode to the coding used in camera mode is made using the following steps:

If in a two-frame raster, the first picture is in film mode and the second picture is in camera mode, add at the beginning of the second frame, a sub-field having a weight such that the total activation duration of the sub-fields of the first frame and said sub-field is substantially equal to the total activation duration of the sub-fields of two groups of subfields of a camera mode picture,

Code the second picture using two groups of sub-fields with a total number of sub-fields less than the total number of subfields for a camera mode picture and a total activation duration equal to the time period for displaying a camera mode picture, then

Code the following pictures using two groups of sub-fields with a total number of sub-fields having a total activation duration equal to the time period for displaying a camera mode picture.

8. Apparatus wherein it adapted to carry out the method according to claim 1.