Method for inserting and detecting electronic watermark data into a digital image and a device for the same

DETAILED DESCRIPTION It is an object of the present invention to provide an electronic watermark data inserter and detector where, even when plural electronic watermark data are inserted into an image, the electronic watermark data can be inserted without negation each other, and at the time of detection, the electronic watermark data can be detected properly.
In the method for inserting identification data (electronic watermark data) according to the present invention, an image is frequency-transformed for each block of j.
times.
k pixels (where j and k are natural numbers), and when the electronic watermark data are inserted into the frequency components transformed, the electronic watermark data are inserted for each block after the kinds of the electronic watermark data to be inserted are changed, so that the electronic watermark data are inserted without negation each other and detected for each block.
More particularly, an electronic watermark insertion position table is provided indicating which kind of electronic watermark data is inserted into which block in an image, and an applicable electronic watermark data is inserted into the area which is shown in the insertion area table.
When the electronic watermark data is detected, the electronic watermark extraction position table similar to that when inserted is used to detect the electronic watermark data.
In the present invention, when a plurality of electronic watermark data are inserted into an image, different electronic watermark data are inserted into for each block, so that the electronic watermark data can be inserted without interference of the different electronic watermark data and negation each other, and also the electronic watermark data can be detected properly even when a plurality of electronic watermark data are embedded.