MOST LIKELIHOOD ESTIMATION OF JPEG QUANTIZED VALUE

摘要

PROBLEM TO BE SOLVED: To provide a system and a method which process an image without requiring information showing whether or how the image has been previously compressed. SOLUTION: Quantized values of image blocks of a decompressed image are determined and a compressing method which has been used to compress the decompressed image to be processed is identified. The method and device are particularly useful to determine whether or not a decompressed image was previouly compressed by the JPEG compression technique by retrieving a DCT coefficient and determining a quantized value, and determining the original DCT coefficient of the compressed and decompressed image.