Abstract:

A semi-fragile digital watermarking algorithm for color image tamper detection and recovery is proposed. Firstly, the color image is converted from RGB space to YCbCr space. Secondly, recovery signals are extracted and embedded into the middle and high-frequency wavelet coefficients of the chrominance components (Cb and Cr), then the L+1 level wavelet coefficients of the Y component are modulated into detection watermarking, which will be embedded into the low frequency coefficient of the Y component. When we authenticate, authentication watermarking is extracted from the Y component, the tampered positions are identified, and then recovery singles are extracted from the Cb and Cr components to restore the tampered areas. Simulation results show that our algorithm can  not only be used in color image authentication and recovery but is also fragile to regular manipulation.

Key words: semi-fragile watermarking;color image;wavelet transform;image recovery