| 摘要 |
PROBLEM TO BE SOLVED: To easily embed multi-bit information such as a digital signature in a small sized picture (graphic mark) using an electronic watermark. SOLUTION: An image is converted into frequency expression, and the value of the amplitude or phase of a cosine wave is displaced by bits to be embedded. That is, the coefficient values of the preliminarily decided elements of a DCT coefficient matrix 42 representing a picture block (8×8 pixels) 41 to be embedded out of a whole picture 43 are displaced by bits to be embedded. Also, not only the bits of information to be embedded but also the bits of the result of the rearray, conversion, or arithmetic operation of the bits can be obtained as the embed information to be displaced. Also, the bits to be displaced can be decided on the basis of the value of the amplitude and phase of another cosine waver or the value of the amplitude and phase of the cosine wave. |
