Method and device for processing video pictures
AssigneeThomson Licensing
InventorsCédric Thebault, Carlos Correa, Rainer Zwing
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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.
Claims10
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,
- wherein the split pixel values and the dithering levels are selected such that, if the sum of the number of bits having a different state in the subfield code word of the pixel value V1 and the subfield code word of the pixel value V2 associated to the first split pixel value and the number of bits having a different state in the subfield code word of the pixel value V1 and the subfield code word of the pixel value V2 associated to the second split pixel value is greater than or equal to a first threshold, the sum of the absolute differences between the dithering level of each split pixel value and ½ is made greater than a second threshold.
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], and
- coding 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,
- wherein the splitting means and the spatial dithering means are controlled in order that, if the sum of the number of bits having a different state in the subfield code word of the pixel value V1 and the subfield code word of the pixel value V2 associated to the first split pixel value and the number of bits having a different state in the subfield code word of the pixel value V1 and the subfield code word of the pixel value V2 associated to the second split pixel value is greater than or equal to a first threshold, the sum of the absolute differences between the dithering level of each split pixel value and ½ is made greater than a second threshold.
Dependencies are inferred from the claim text.