Abstract: An image signal transmitting system uses the difference between image frames, which can transmit lots of information in a small amount of data, by transmitting the acutal moving areas which are extracted by using two change detecting masks and whose contours and textures are encoded for human visual perception. A larger amount of information is expresssed by a smaller amount of data by extracting the motion in a unit of frames, not in a unit of blocks, and expressing a converted portion by its contour and texture to facilitate the recognition of the converted portion.

Abstract: A videophone system for providing videophone service within narrow band digital network, based on pipelined processing elements, includes source codec means coupled to the image bus, including numerous processing elements of which processing element has DSP (Digital Signal Processor) module, local memory module coupled to the DSP module, FIFO (First Input First Output) memory module coupled to the DSP module and the local memory module, and image bus interface module coupled to the DSP module and the local memory module and the image bus, wherein communications between the processor elements is performed via the pipeline and common memory means coupled to the VME bus and the image bus, for storing message data for synchronization and communication between the processing elements.