| 摘要 |
<p>The present invention provides a method and a system for embedding and extracting image digital watermark. The watermark embedding method comprises: carrying out DWT to the original carrier digital image to obtain two intermediate-frequency coefficient matrixes; first carrying out DCT, and then carrying out DWT to one of the two intermediate-frequency coefficient matrixes, to obtain a first low-frequency coefficient matrix; carrying out DWT to the other intermediate-frequency coefficient matrix, to obtain a second low-frequency coefficient matrix; adjusting the magnitude of the first low-frequency coefficient and the second low-frequency coefficient at the respective same embedded position of the first low-frequency coefficient matrix and the second low-frequency coefficient matrix, according to the watermark numerical value to be embedded, so that the magnitude relationship of the two adjusted low-frequency coefficients fulfills the preset corresponding relationship between the embedded numerical value and the magnitude relationship of the two low-frequency coefficients. It is only necessary to carry out inverse transform according to the watermark embedding method, and the original carrier digital image is unnecessary, when extracting the watermark.</p> |
