Abstract: The invention relates to a method for processing video pictures for display on a display device having a plurality of luminous elements corresponding to the pixels of a picture wherein the time of a video frame or field is divided into a plurality of N sub-fields during which the luminous elements can be activated for light emission in small pulses corresponding to a sub-field code word of n bits used for coding the p possible video levels lighting a pixel, comprising the steps of: determining if pictures are static pictures or moving pictures, in case of static pictures, processing video pictures using a first sub-field encoding method adapted to pictures when no motion is detected, and in case of moving pictures, processing video pictures using a second encoding method reducing dynamic false contour effect adapted to pictures when motion is detected. The invention applies to plasma display panels.

Abstract: The present invention relates to a new method for generating motion compensated picture by interpolating two consecutive source pictures without using motion estimator. For a given pixel to be interpolated, all displacements within a given search range between former and next frame are considered and for each displacement the displaced block difference is calculated. The pixel value is then equal to the sum of each averaged pixel pair within the search range weighted by a correlation coefficient function of the corresponding displaced block difference.

Abstract: The present invention relates to a method for processing data of a picture to be displayed on a display panel with persistent luminous elements in order to reduce load effect in said display means. The method comprises the following steps: computing, for each subfield, the amount of activated luminous elements in each line of luminous elements of the display panel, called line load, calculating, for each subfield, the maximal difference of line loads of two consecutive lines of the display panel, and selecting, for each subfield, a sustain frequency in accordance with its maximal load difference in order to reduce line load effect.

Abstract: The present invention concerns a method for transcoding a N bits word into a M bits word with M<N. The invention is applicable in various fields and more particularly in the display field. The method comprises the following steps: -breaking down the N bits word into an exponent part and a mantissa part having each a size which varies according to the value of said N bits word, the size of the mantissa part increasing with the value of said N bits word, and -encoding the exponent part of the N bits word into a variable number of bits A and removing, if need be, least significant bits of the mantissa part in order to obtain a mantissa with a variable number of bits B, with A+B=M.

Abstract: The gravity centred coding shall be improved with respect to false contour effect disturbances on plasma display panels for example. Therefore, there is provided a GCC code (gravity center coding) and a motion amplitude of a picture or a part of a picture. Furthermore, there is provided at least one sub-set code of the GCC code. The video data are coded with the GCC code or the at least one sub-set code depending on the motion amplitude. Thus, it is possible to reduce the number of coding levels if the motion increases. A further improvement can be obtained by using texture information for selecting the GCC code.

Abstract: The present invention is particularly useful in the field of plasma display panels (PDPs) or other display devices wherein each video level is represented by a combination of bits according to a specific coding. In this case, when the algorithms used to improve picture quality are based on data stored in memories such as look-up tables (LUTs), the size of such tables may be quite huge. To improve picture quality in PDPs, an algorithm using metacode LUTs has been developed, using data stored in look-up tables. The invention proposes a way to reduce the amount of look-up tables needed for implementing metacodes. According to the invention, only some look-up tables of low size are stored and the other ones are achieved by extrapolation.

Abstract: Overheating while enabling a full flexibility in the display usage should be avoided. This object is solved by a method for avoiding the overheating of a driver circuit in a plasma display panel wherein the driver circuit receives serially display data in form of a sequence of sub-field data bits and forwards parallelly the display data in the form of data blocks each consisting of a predefined number of sub-field data bits, the method comprising the steps of counting sub-field data bits the value of which differs from that of a neighbouring or preceding sub-field data bit and providing a respective counting signal indicative of heat contributions of sub-field data bits and, if said counting signal is above a pregiven threshold, taking countermeasures for reducing said temperature.

Abstract: The invention relates to a method and apparatus for processing video pictures, in particular for large area flicker effect and false contour effect reduction. This method concerns a new coding called Parallel Peak Coding. The general idea of the Parallel Peak Code is to have almost always the same energy in two packets of light and to encode the code words for these two packets differently so that changes in sub-field code word will not appear in the two packet code words simultaneously.

Abstract: Response fidelity problems appear for some specific video levels at PDP borders. The reason is that some cells at the border of the PDP panel are not completely closed and pollute when switched ON neighbouring cells being OFF. Therefore, it is suggested to encode the video levels in the border area in a specific way. Especially, for critical sub-fields within the code it is forbidden to insert a binary 0 between two binary 1. Thus, the neighbourhood of critical sub-fields being ON and OFF is avoided. Preferably, the specific border coding is performed under the control of an average power management and codewords being not used are recreated by dithering.

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.

Abstract: A picture quality when reducing the brightness or the contrast of the picture on a plasma panel shall be improved. For this purpose there is provided a driving apparatus including brightness/contrast control means for receiving video input data for modifying the video levels of the video input data in accordance with external adjustment data and for outputting modified video data. First power measurement means measure a power level of the modified video data and supply a first power level. Second power measurement means measure a power level of the video input data and supply a second power level. Generator means generate a third power level comprised between the first power level and the second power level or equal to the larger one to data processing means. The data processing means calculate the maximum number of sustain pulses per frame applicable to the modified video data on the basis of the third power level and control the display of the modified video data on the plasma display panel.

Abstract: Plasma Display Panels (PDP) are becoming more and more interesting for TV technology. Due to the larger size of PDPs, with larger viewing angle the large area flicker effect will become more serious in the future, in particular when handling 50 Hz video standards. This invention proposes a different sub-field organisation, with different coding, which reduces large area flicker artefact, and which is characterised by: 1. Grouping of sub-fields (SF) in 2 sub-field groups (G1, G2), of similar structure. 2. Adjusting the starting times of the two sub-field groups to a time raster corresponding to a doubling of the frame repetition rate by adding a first blanking period of a first dedicated length behind the last sub-field of the first sub-field group and a second blanking period of a second dedicated length behind the last sub-field of the second sub-field group.

Abstract: The invention concerns a video processing for improving the picture quality of picture which are displayed on display devices like plasma display panels and all kind of display devices based on the principle of duty cycle modulation of light emission and for reducing the average power dissipation. The basic idea behind the invention is to generate only the required amount of sustain pulses that effectively produce light and to avoid generating unnecessary sustain pulses. To this end, the video range of the input video is increased in order to be equal to a nominal range, 255 in the case of a 8-bit coding, and a power level mode with a reduced number of sustain pulses is selected to keep constant the brightness of the image. The number of sustain pulses that do not produce light is reduced.

Abstract: The invention relates to a method for power level control of a display device and an apparatus for carrying out the method. Classically, a power level mode defining a subfield organization to be used for subfield coding is selected as a function of the average power level of the picture to be displayed for keeping constant the power consumption of the display device. According to the invention, it is proposed to select the power level mode as a function of the input frame frequency in such a way as to have as little as possible deviations from nominal peak white and full white values at the same time that an overloading of the panel power supply is prevented. More particularly, the number of sustain pulses within the video frame and selected by the power level mode is modified as a function of the input frame frequency.

Abstract: The invention relates to a new method for power level control of a display device and an apparatus for carrying out the method. Classically, the contrast/brightness control and the power management (based on an average power level control) are made independently. These two controls can be contradictory. According to the invention, the power level mode and more particularly the number of sustain pulses within the video frame is selected as a function of the average power level (APL) of the picture to be displayed and the picture control signal representing the desired contrast and/or brightness value.

Abstract: The invention relates to a method and a device for encoding the luminance value of a pixel of a picture into a subfield code word in a display device. It can be applied to every display device using a PWM (Pulse Width Modulation) technology and subfields for displaying video picture. It can be used to compensate for any luminance problem that can be estimated. The general idea of the recursive coding is to encode one sub-field after the other in order to be able to compensate for problems occurring on one sub-field with the other sub-fields. More particularly, the bits of a subfield code word are computed recursively one after the other such that the defects (e.g. line load and/or linearity) in the light emission or luminance generated by a bit of the subfield code word can be compensated by the following bits of the subfield code word.

Abstract: The present invention relates to a coding method intended to improve the performance of GCC coding based on the temporal centre of gravity of displayed video codes. According to the invention, the number of video levels that can be selected in order to implement the GCC coding is increased by increasing the number of subfields in the video level display frame. This increase in the number of subfields is made possible by simultaneously addressing the cells of at least two adjacent rows of the PDP during at least two subfields of the video image display frame.

Abstract: The invention is related to a new kind of pre-processing for plasma display panel control. The plasma display technology has the drawback of a reduced grey scale portrayal. This is due to the fact that contrarily to CRTs where luminance is approximately quadratic to the applied cathode voltage, luminance is linear to the number of discharge pulses in PDPs. Therefore, an approximately quadratic degamma function has to be applied to the input video signal components R,G,B before sub-field coding can be done. Truncation to 8-bit video data is required, so that the effect of the degamma function cannot be fully maintained. Especially in the region of small video levels, where the eye sensitivity is high, the grey scale portrayal is poor. According to the invention it is proposed to use a new kind of dithering, adapted to the PDP specialities to improve the grey scale portrayal. These adaptation includes three dithering specialities which can be used singly or in combination. These are: cell-based dithering, i.

Abstract: The invention relates to a method for processing video data to be displayed on a display device having a plurality of luminous elements corresponding to the pixels of a video picture, wherein an error diffusion step is applied to at least a part of said video data to refine the grey scale portrayal of said video picture, said error diffusion step comprising, for each current pixel of said part of video picture, a step of truncating the value of the corresponding video data and a step of diffusing the truncation error to at least one neighboring pixel. According to the invention, a noise is inserted on the error before and/or after its diffusion to the neighbouring cells. Owing to this principle no static pattern should be visible, improving the overall picture quality.

Abstract: The present invention relates to a method and an apparatus for processing video pictures especially for dynamic false contour effect and dithering noise compensation. The main idea of this invention is to divide the picture to be displayed in areas of at least two types, for example low video gradient areas and high video gradient areas, to allocate a different set of GCC (for Gravity Center Coding) code words to each type of area, the set allocated to a type of area being dedicated to reduce false contours and dithering noise in the area of this type, and to encode the video levels of each area of the picture to be displayed with the allocated set of GCC code words. In this manner, the reduction of false contour effects and dithering noise in the picture is optimized area by area.