A blind watermarking method based on cellular automata transform domain

Abstract

A blind watermarking method using cellular automata transform (CAT) is proposed. A binary watermark is embedded in a certain sub-band, which is further subdivided into non-overlapped blocks, of 2-level CAT transformed of a host image. Each block embeds a watermark bit with two patterns (P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> , P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> ) only differing in sign. The detector is blind, determining the value of a watermark bit on the sign of the correlation between the corresponding block and one of the two patterns. Three keys are used to enhance the security of the proposed scheme. The proposed method has a reasonable degree of watermark imperceptibility, which can be notified from the high PSNR and MSSIM. The results show that the proposed method is robust against most common image operations.