The Digital Watermarking Technique Has Attracted Increased Interests on the past Decades. the General Framework of Robust Watermarking Is Described, and some Typical Robust Digital Image Watermarking Patents Are Surveyed in this Paper. the Main Principles and Functions of these Patents Are Reviewed and Discussed. then a Summarization about these Patents, the Challenge and Potential Research Directions in the Future Are Given Briefly.

Because of the characteristic of the gray relation analysis and the advantage of the alpha-trimmed mean filter, an efficient technique for mixed noise removal in images was proposed. This algorithm can adjust the filter coefficients adaptively according to various pieces of the image features. Experiment results show that the proposed algorithm which greatly improved efficiently, it not only can remove mixed noise in image, but also can keep the details of the image.