SYMBOL COMPRESSION METHOD AND DEVICE, STATISTICAL CODER (OPTIONS) Russian patent published in 1999 - IPC

FIELD: compression of images, including graphic pallet ones, using statistical coder and parallel statistical coder. SUBSTANCE: input symbols are quantized in M-th alphabet in two levels basing on context model of input data where double-level quantization is chosen to ensure adequate compression by binary coder. Particular double-level quantization is found from re-indexing table which displays each input symbol in binary value. Display image is determined from images to be compressed and is usually transmitted with compressed images as insert. Display image is, essentially, local minimum of bit-by-bit entropy of double-level quantization. Symbols can be concurrently converted into compressed ones with or without input re-indexing, with input symbol positions buffered and re-ordered when it is necessary to ensure that bits required for context of decoded bit are available before decompressor encodes decoded bit. Decompressor has means for backward re-ordering so that decompressor output is same as compressor input. EFFECT: improved accuracy of initial signal recovery from compressed signal. 24 cl, 14 dwg