Method and device for protecting displays from burn-in effect

Abstract

The invention concerns a device and a method for protecting display panels from burn-in effect when displaying a still picture over a long period of time. The image processing method according to the invention comprises a step of shifting pictures by a pattern at a pixel shift frequency characterized in that said frequency is changed for a group of at least one picture depending on a motion degree of said group.

Description

4. BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the invention will appear with the following description of some of its embodiments, this description being made in connection with the drawings in which:

FIG. 1 depicts an example of a pixel shift pattern where the whole picture is shifted either diagonally downwards or diagonally upwards;

FIG. 2 depicts the shifting of lines of pixels according to the pixel shift pattern of FIG. 1;

FIG. 3 depicts a diagram representing the pixel shift-frequency as a function of the motion data average; and

FIG. 4 depicts the flowchart of the method according to the invention.

Claims

1. Method of image processing in a picture display device comprising a step of shifting pictures by a pattern at a pixel shift frequency wherein said frequency is changed for a group of at least one picture depending on a motion degree of said group.

2. Method according to claim 1, wherein said pixel shift frequency value is inversely proportional to said motion degree.

3. Method according to any of claims 1, wherein it comprises the following steps: associating a pixel shift frequency to each motion degree;computing a motion degree for a group of at least one picture; andselecting the pixel shift frequency associated to said computed motion degree.

4. Method according to claim 3, wherein said motion degree is computed by the following steps: collecting n motion data samples relating to m pictures, m<=n; andaveraging said n samples to get a motion data average for said m pictures.

5. Method according to any of claims 1, wherein it comprises the following steps: defining K motion ranges;associating a pixel shift frequency to each motion range;computing a motion degree for a group of at least one image;selecting the motion range including the computed motion degree; andchanging pixel shift frequency with the pixel shift frequency associated to said selected motion range.

6. Method according to claim 5, wherein the pixel shift frequency is changed only if at least T consecutive computed motion degrees belong to the same motion range.

7. Method according to claim 6, wherein said motion degree is computed by the following steps: collecting n motion data samples relating to m pictures, m<=n; andaveraging said n samples to get a motion data average for said m pictures.

8. Method according to claim 1, wherein the pixel shift pattern consists in shifting the whole picture p pixels diagonally downwards up to a maximum of Q pixels and then shifting it p pixels upwards or inversely, p>=1 and Q being a multiple of p.

9. Picture processing apparatus, wherein it comprises motion processing means for computing a motion degree and image processing means for shifting pictures by a pattern at a pixel shift frequency, said frequency being changed for a group of at least one picture depending on the motion degree of said group.

10. Picture processing apparatus according to claim 9, wherein a look-up table is used to associate a pixel shift frequency to a motion degree.