ELECTRONIC WATERMARK EMBEDDING METHOD, ELECTRONIC WATERMARK EMBEDDING APPARATUS, PROGRAM, AND COMPUTER-READABLE RECORDING MEDIUM

摘要

An electronic watermark embedding method in which the processing speed of when electronic watermark information is embedded in image data is improved, deterioration of the image data after the electronic watermark information is embedded is reduced, and the electronic watermark information is embedded in JPEG compressed image data. The electronic watermark embedding method comprises a first step of generating DCT data on an electronic watermark pattern image produced by converting the electronic watermark information into a pattern image; a second step of generating DCT data in the JPEG compressed image data by performing entropy decoding and dequantization of the JPEG compressed image data in which the electronic watermark information is to be embedded; a third step of generating DCT data by combining the DCT data on the electronic watermark pattern image generated in the first step and the DCT data in the JPEG compressed image data generated in the second step; and a fourth step of generating the JPEG compressed image data in which the electronic watermark information is embedded by performing quantization and entropy coding of the DCT data generated in the third step.