METHOD, DEVICE AND PROGRAM FOR EMBEDDING DIGITAL WATERMARK FOR ALTERATION DETECTION, METHOD, DEVICE AND PROGRAM FOR ALTERATION DETECTION USING DIGITAL WATERMARK, AND RECORDING MEDIUM HAVING THESE PROGRAMS RECORDED THEREIN

摘要

PPROBLEM TO BE SOLVED: To provide a method for embedding a digital watermark for alteration detection, which is capable of detecting alteration of video images by embedding the digital watermark without spoiling the beauty. PSOLUTION: An input video image is subjected to YCbCr conversion, down-sampling, DCT, and DCT coefficient quantization in normal JPEG coding process (S31, S32), and redundancy is given to digital watermark data to obtain error detection code data (S33, S34), and this data is converted to encrypted code data (S35) by a prescribed encryption method, and DCT blocks of a selected color component are divided into groups (S36, S37), and the encrypted code data is embedded into the DCT block belonging to each group (S41), and entropy compression of quantization coefficients after the completion of embedding is performed in the same manner as the normal JPEG coding process, and the result is shaped so as to conform to a prescribed JPEG format, and thus JPEG coding is completed (S42, S43). PCOPYRIGHT: (C)2010,JPO&INPIT