Research on spread spectrum watermarking algorithm resisting image-cropping based on baker's transformation

In order to improve the ability resisting image-cropping of spread spectrum watermarking,this paper proposed a new spread spectrum watermarking algorithm based on baker's transformation.First,it did baker's transform of the watermarking image to scramble it,then spread the image with a PN sequence so that it could get a watermarking sequence with the ability resisting image-cropping.In the end embed the sequence into the low frequency band of the carrier image DCT domain to complete the embedding process.When checking the watermarking,cropped different area of the carrier image and calcula-ted the correlation value between the extracted watermarking image and the original image.The experimental result demonstrates that the algorithm can not only resist large area cropping,but also manifest a good robustness when facing other attacking methods.