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: 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: 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 luminous elements of the three colours red, green and blue of a plasma video display have different time responses. Therefore, a coloured trail/edge appears behind and in front of the edges of a moving object. In order to reduce the disturbing character of such coloured trails/edges, correcting the video data for blue and red phosphor elements to compensate for the different time responses discolor them. Then only a discolored trail/edge appears which is less disturbing.

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.

Abstract: A method for processing video data for display on a display device having a plurality of luminous elements comprising: applying a dithering function based on single ones of said luminous elements to at least part of said video data to refine the grey scale portrayal of video pictures of said video data, computing at least one motion vector from said video data, and changing at least one of the phase amplitude, spatial resolution and temporal resolution of said dithering function in accordance with said at least one motion vector when applying the dithering function to said video data.

Abstract: The invention relates to a method for optimizing brightness in a display device having a plurality of luminous elements corresponding to the pixels of a picture, wherein the time duration of a video frame or video field is divided into a plurality of sub fields during which the luminous elements can be activated for light emission with sustain pulses corresponding to a sub field code word which is used for brightness control, the total number of sustain pulses being determined in view of a selected power mode function of picture load the method including the following steps: setting a threshold value in relation to the picture load, comparing, for a frame, the number of the current sustain pulse to said threshold value, if the number of the current sustain pulses is below the threshold value, the sustain pulses are generated at a fixed frequency, if the number of the current sustain pulses is above the threshold value, the sustain pulses are generated at an evolving frequency.

Abstract: The present invention relates to a method for processing video pictures for display on a display device comprising a plurality of lines constituted by luminous elements called cells corresponding to the pixels of a picture, wherein the time duration of a video frame is divided into a plurality of sub-field periods during which the cells can be activated for light emission, a sub-field period being divided into an addressing period wherein the plurality of lines is scanned line by line, a sustaining period and an erasing period, wherein, in the addressing period, the addressing time is different from one line to an other. The invention is mainly used in PDP technology.

Abstract: The invention relates to a method for processing data of video pictures for displaying the pictures on a display device like a Plasma Display Panel. The existing false contour effect compensation methods which make a false contour compensation based on shifting sub-field code word entries along the direction of the motion vector of a current pixel, produce an artifact in the pictures, in case of object crossings. In the appearing area there is a lack of light generation. The invention solves this problem by checking whether an area exists in the picture which is currently hidden but will appear in a next frame and providing an adapted compensation method for “hole filling”. The invention also gives a solution for an improved compensation method which is based on a dragging of sub-field code word entries along a motion vector direction to a current pixel.

Abstract: The invention relates to a method for driving a display panel comprising a matrix array of cells which could be “ON” or “OFF”, wherein, to display an image, a video frame is divided into N sub-fields, each sub-field comprising at least an addressing period and a sustaining period, the addressing period being constituted either by a selective writing period or a selective erasing period and the duration of the sustaining period corresponding to the weight associated with said sub-field. According to the invention, the sub-fields successively alternate between a sub-field with a selective writing period and a sub-field with an erasing period. The invention is applicable to PDPs.

Abstract: The visible pattern of classical matrix dithering in case of applications with moving pictures and static pictures shall be suppressed more effectively. Therefore, it is proposed to change a dithering pattern in the dithering block non-periodically. This can be effected by a random generator which may be activated by a motion detector. The motion detector enables to individually alternate the dithering function depending on moving or static pictures.

Abstract: The invention is related to a new kind of plasma display panel control. A known principle for PDP control is based on a combination of sub-field addressing and priming. Within the priming period all the plasma cells of the panel are pre-excited by a strong voltage pulse. This treatment of the cells produces a slight background luminance which is a drawback for picture quality aspects because the achievable contrast is reduced. According to the invention it is proposed to use self-priming sub-fields and refreshing sub-fields instead of this hard priming period. With these concepts it is assured that the cells which ought to be black remain black. Self-priming sub-fields reduce or eliminate the need for priming, thus making dark areas darker, while refreshing sub-fields, can be addressed faster. In practice, the number of refreshing sub-fields in a frame period is higher than the number of the self-priming sub-fields. Therefore, the total addressing time can be reduced with this new technique.

Abstract: Plasma Display Panels are becoming more and more interesting for TV technology. One important criterion for picture quality is the Peak White Enhancement Factor PWEF. In a previous patent application a method for power level control in a display with which the PWEF can be increased has been proposed. With an increased PWEF the problem of local overheating of plasma cells may occur. This invention proposes a protection circuit, which deals with this problem. For protecting the plasma display against local overheating, there is provided a method, which performs the steps of local power value determination, local temperature estimation, maximum local temperature determination and maximum power level limit determination. The power level limit influences the power level control process in the display device so that local overheating is avoided and the highest possible PWEF can be used. The invention also concerns a corresponding apparatus for carrying out the proposed method.