METHOD FOR INSERTING ELECTRONIC WATERMARK DATA, ITS DEVICE AND ELECTRONIC WATERMARK DATA DETECTOR

摘要

PURPOSE: To insert an electronic watermark into an image without degradating the image quality and to enhance its detection efficiency by selecting one kind of electronic watermark data according to a picture type and inserting the selected electronic watermark data into data after discrete cosine transform(DCT). CONSTITUTION: Block data 102 with a size of 8x8 pixels is taken out from an original image 101 and the DCT transformer is performed by a DCT transformer 103. Next, the DCT coefficient of the DCT transformed block data 102 is quantized by a quanitizing device 104 according to the picture type from a picture determining part 106. Next, the electronic watermark data W (j) coinciding with a position where 8x8 block data are taken out and the picture type is taken out from an electronic watermark data table 108 and the watermark data are inserted into the data after quantization to be outputted by the quantizing device 104 by an electronic watermark data inserting device 105. Such as operation is performed for the entire image to insert the electronic watermark data.