A Study Of Watermarking Algorithm For Halftoning Image

The images printed on paper are existed in all of our life.They have done a great favor to share and communicate the information,and they also have been persecuted by the illegal copy more and more.So the author and bookman's profits are lost badly. As a new technique of copyright protection for printed images,the watermarking can solve the problem effectively.Halftoning is an especial technique in printer,which can convert digital con-tone images with n-level grayscale into special binary images.The watermark is embedded into halftoning image can resist the process of printing,scanning and cropping attacks.Having analyzed the properties of the halftoning edge,texture area,smooth area and human vision system,the two kinds of watermarking algorithms for halftoning image are proposed.The first one has embedded watermark into halftoning image based on the edge and model in the process of halftoning.The second one has segmented the halftoning image into many blocks,and the watermark is embedded with different rules which are decided by the property of each block.A large amount of experiments show the two algorithms have good performance on invisibility and robustness if only embed appropriate watermark into the halftoning image.And the watermark can be correctly extracted when the watermarked image is printed and attacked by random marking,cropping and spotting.