Copyright labeling of printed images

Digital Watermarking is a labeling technique for digital images which embeds a code into the digital data so the data is marked. Watermarking techniques previously developed deal with on-line digital data and have been developed to withstand digital attacks such as image processing, compression and geometric transformations. In this paper we deal with printed images rather than on-line data. An important issue is to intercept and prevent forgery in printed material such as currency notes and bank checks and to track and validate sensitive and secret printed material. Watermarking in such printed material can also be used for embedding additional informatice information (source, date, type of transaction etc). In this work we propose a method of embedding watermarks in printed images by inherently, exploting the printing process. The method is visually unobtrusive to the printed image, the watermark is easily extracted and is robust under reconstruction errors. The decoding algorithm is automatic given the watermarked image.