Abstract: The invention corrects display faults due to the disparities between the phosphors of a display device. The correction is carried out by image processing. The invention provides a method for displaying a sequence of video images on a phosphor device comprising at least two types of phosphors together with the device comprising the means for implementing this method. The correction is carried out by computing an intermediate image between two successive images, then by displaying one of the two successive images on one type of phosphor and by simultaneously displaying the intermediate image on another type of phosphor.

Abstract: Since the phosphor lag effect results from the slowness of the green and red phosphors and since it is not possible to make these phosphors faster, the blue one has to be made slower in order to reduce the color trail effect. Therefore, a part of the blue component is artificially delayed. Only a certain percentage of the blue component of the actual frame is transmitted during the actual frame, whereas the rest of the blue component will be transmitted during the next frames. The dynamic false contour effect introduced by this video processing may be compensated by subfield shifting.

Abstract: A videophone system having an electronically controlled shutter to vary the amount of light falling onto the target by a shutter, e.g., for a greater or lesser length of time during a short exposure time rather than b y means of a controlled mechanical aperture. Data reduction is used for the transmitted signal, a control circuit is used for the exposure time, and the mains power supply, which produces ambient light, are coupled by means of a PLL circuit so that the exposure time occurs at the same phase of the mains voltage. In this way, interference occurring when data reduction is used for the signal to be transmitted is avoided and macroblocks are not formed when no difference signal is present.