Method and device for processing video pictures

Abstract

The invention relates to a method for processing video pictures data for display on a display device having a plurality of luminous elements corresponding to the pixels of a video picture. The invention is related to every kind of display devices based on the principle of duty cycle modulation (pulse width modulation) of light emission and comprising a data driver. The aim of this method is to reduce the data driver overheating by optimizing the dithering of the pixel values of the video pictures. According to the invention, the pixel values used for dithering are chosen for reducing the state changes between successive bits of subfield code words of adjacent luminous elements.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description. In the drawings:

FIG. 1 shows the overall electronic structure of a plasma display panel;

FIG. 2 shows the global functioning of the data driver of the plasma display panel of FIG. 1;

FIG. 3 shows the critical data pattern introducing an overheating of the data driver;

FIG. 4 shows the equivalent number of chequered patterns for every dithering level;

FIG. 5 shows the equivalent number of chequered patterns for every pixel value between 2 and 232;

FIG. 6 shows the partition between the first peak and the second peak for all the pixel values between 0 and 255;

FIG. 7 shows the equivalent number of chequered patterns for every pixel value between 0 and 255 when the inventive method is applied;

FIG. 8 shows a block diagram of a first possible circuit implementation of the inventive method; and

FIG. 9 shows a block diagram of a second possible circuit implementation of the inventive method.

Claims

1. Method for processing video pictures data for display on a display device having a plurality of luminous elements corresponding to the pixels of a video picture, the luminous elements being organized in columns and lines, 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, a sub-field code word corresponding to said plurality of sub-fields being used for encoding the pixels values in which each bit can have either an “OFF” state or an “ON” state such that each luminous element is activated during a subfield when the corresponding bit of sub-field code word has an “ON” state, comprising: a splitting step for splitting each pixel value of the picture to be displayed into at least first and second split pixel values, each split value being associated to a group of subfields of said plurality of subfields,a spatial dithering step for associating to each split pixel value V one dithering level L used to dither between two different pixel values V1 and V2 that can be coded by the associated group of subfields such that V=(1−L)×V1+L×V2 with V1<V2and L∈[0, 1],a coding step for coding the pixel values V1 and V2 into sub-field code words, each bit of the sub-field code word having a bit state,

2. Method according to claim 1, wherein said second threshold is greater than or equal to ¼.

3. Method according to claim 1, wherein the first threshold is zero.

4. Method according to claim 1, wherein the first threshold is different from zero.

5. Method according to claim 1, wherein the second threshold is equal to ½.

6. Method according to claim 1, wherein each pixel value of the picture to be displayed is split into two first and second split pixel values, the first and second split values being associated to first and second groups of subfields respectively.

7. Method according to claim 6, wherein the dithering level for the first split pixel value is ½ and the dithering level for the second split pixel value is 0 or the dithering level for the first split pixel value is 0 and the dithering level for the second split pixel value is ½ or the dithering level for the first and second split pixel values are different from ½.

8. Method according to claim 1, wherein the number of subfields of the first group of subfields is substantially equal to the number of subfields of the second group of subfields.

9. Method according to claim 6, wherein the first and second pixel values are substantially equal.

10. Device for processing video pictures data for display on a display device having a plurality of luminous elements corresponding to the pixels of a video picture, the luminous elements being organized in columns and lines, 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, a sub-field code word corresponding to said plurality of sub-fields being used for encoding the pixels values in which each bit can have either an “OFF” state or an “ON” state such that each luminous element is activated during a subfield when the corresponding bit of sub-field code word has an “ON” state, comprising: splitting means for splitting each pixel value of the picture to be displayed into at least first and second split pixel values, each split value being associated to a group of subfields of said plurality of subfields,spatial dithering means for associating to each split pixel value V one dithering level L used to dither between two different pixel values V1 and V2 that can be coded by the associated group of subfields such that V=(1−L)×V1+L×V2 with V1<V2 and L∈[0, 1], andcoding means for coding the pixel values V1 and V2 into sub-field code words, each bit of the sub-field code word having a bit state,