In the attribute detection apparatus in the system of the present
invention, an inputted image is transformed by DCT means to extract an
estimation value of the embedded electronic watermark data in frequency
space. Then, the statistical similarity between known electronic
watermarks and the extracted electronic watermark data are calculated. The
attribute change apparatus in a system of the present invention comprises
a selector, an insert data register for storing the output of the
selector, a brightness register for storing the brightness signal of the
inputted image, a color difference register for storing the color
difference signal of the inputted image, and adder for adding the output
of the color difference register and the output of the insert data
register. Here, the selector selects one of the insert data stored in a
plurality of memory areas on the basis of the attribute inputted from
attribute detection apparatus.
