IMAGE COMPRESSING DEVICE, IMAGE EXTENDING DEVICE AND TRANSMISSION EQUIPMENT

摘要

PROBLEM TO BE SOLVED: To properly extend a quantized subordinate image only for the required subordinate image by enciphering its required part. SOLUTION: A source image is divided into subordinate image groups of N hierarchies (1 to N) by a conversion encoding part 1. A quantizing part 2 respectively quantizes the subordinate image groups outputted from the conversion encoding part 7. An enciphering part 3 receives a block number to be enciphered in the source image as an enciphering part designate signal and enciphers a block having the prescribed number, in the case of dividing the subordinate image group of each hierarchy outputted from the quantizing part 2 into the blocks of pixels. Then, the enciphered block number is outputted as partial enciphered information. An entropy encoding part 4 performs entropy encoding to the output from the enciphering part 3. Thus, the image can be partially enciphered, while effectively utilizing the reversible and inreversible continuity of wavelet without performing excessive compression/extension.