| 摘要 |
Compressing image data includes partitioning original image data into non-overlapping blocks, transforming the non-overlapping blocks into Discrete Cosine Transform (DCT) coefficient blocks, and quantizing the DCT coefficient blocks to generate the quantized DCT blocks. A block-classification strategy is used to classify DCT-blocks into the flat-block and the normal-block. The quantized DCT blocks are then embedded with watermarks. And the watermarks are checked to determine whether the image data is tampered. Thus, the damaging problem of clipping errors caused by normailization in spatial domain can be reduced significantly.
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