SYSTEM AND METHOD FOR INSERTING INFORMATION INTO DCT COEFFICIENT

摘要

PURPOSE: To insert a large amount of information into a DCT coefficient being an intermediate data form in a digital picture encoding system following an MPEG standard by providing a total code length restoration means making the total code length of a code generated by the DCT coefficient to be equal to total code length before information is inserted. CONSTITUTION: An information insertion means 1 inserts additional information into original information in one block by changing the value of one or not less than two DCT coefficient from among all DCT coefficients in one block. Namely, the information insertion means 1 inserts information, which is supplied from an insertion information storage means 3 and which is to be inserted into the DCT coefficient of inputted picture data. A total code length restoration means 5 refers to a variable length code table 7 and rewrites a part of DCT coefficient. Thus, total code length, when the DCT coefficient after information is inserted is encoded, is adjusted so as to be equal to total code length when the DCT coefficient prior to information is inserted, is encoded.