Medical Image Digital Watermarking Algorithm Based on DWT-DFRFT

Abstract

In order to solve the security problem of medical information and improve the robustness of watermarking algorithms for medical image, a noval watermarking algorithm based on discrete wavelet transform and discrete fractional fourier transform (DWT-DFRFT) was proposed. First, DWT-DFRFT transform was applied to extract the feature vectors of original medical images. And combined with cryptography technology, the extracted feature vectors are represented by a 32-bit symbol sequence, which is derived from the transformation of 4 * 4 submatrix coefficients of the middle part extracted from the energy distribution after DFRFT transformation. Then, the watermark was encrypted with tent chaotic mapping, and the encrypted binarized watermark was associated with the feature vector to realize zero watermarking and blind extraction. After performed both conventional attacks and geometric attacks on medical images, the algorithm is proved to be robust. The experimental results show that it can resist both conventional attacks and geometric attacks, and performs well under geometric attacks.