A Robust Watermarking Algorithm Based on DCT

Robustness is difficult to resolve in digital watermarking research, and contradicts its stealthiness. So the key of designing robust digital watermarking is selecting watermark embedding positions. Around these problems, we study the robust digital watermarking algorithm based on DCT. By cosine transform, image smoothing based on PDE, and morphology operators (dilation and erosion), we obtain the relative low-frequency regions with small changing which can not be detected easily by human eyes, and then get the embedding positions. The watermark embedded in these positions has a proper consideration on both robustness and invisibility of the watermark. Experiments show that this algorithm is robust to JPEG compression, sharpening, salt and pepper noise, gama correction, a number of regular geometric attacks and other image processing operations