Secure semi-blind watermarking based on iteration mapping and image features

This paper presents a secure semi-blind watermarking technique based on iteration mapping and image features. An image (gray or color) is divided into blocks of fixed size that are analyzed using fractal dimension to determine their properties. The feature blocks containing edges and textures are used to form a feature label. The watermark is the fusion of image feature label and a binary copyright symbol. Arnold iteration transform is employed for constructing the watermark to increase the security. The secure image adaptive watermark is then embedded in the feature blocks by modifying DCT middle-frequency coefficients. The detection and extraction procedure is a semi-blind, i.e., it does not need the original image. Only those who have the original watermark and the key can detect and extract the right watermark, which makes the approach have high security level. Experimental results demonstrate that this algorithm can achieve good perceptual invisibility, adaptability and security. It is also robust against spatial attacks including discarding, scribbling, luminance and contrast changing, and other attacks including low or high-pass filtering, adding noise and JPEG processing. 2004 Pattern Recognition Society. Published by Elsevier Ltd. All rights reserved.