Digital watermarking algorithm based on SVD in DCT domain

Firstly, Original image was divided into blocks and their entropy and standard deviation were calculated. According to HVS characteristics, selected some blocks with larger entropy and smaller standard deviation to embed watermark. Selected blocks are transformed into DCT domain and then operating SVD. The binary watermark image was embedded into the S component of those SVD decomposition after encrypted by chaotic encryption. Due to the watermark was embedded three times, the amount of embedded information is increased. Watermark obtained by selecting best one from three watermarks extracted from watermarked image. The experiment results show the algorithm has good invisibility and robustness to JPEG compression, image add noise, median filtering, cropping and other image processing operations.