Variable Sized Wavelet Analysis for Reversible Image Watermarking Approach

• Main Authors: Chieh-Hsiang Hsu, 許傑翔
• Other Authors: Dr. Yao-Hong Tsai Dr. Chien-Chang Chen
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/14668304946596409163

碩士 === 玄奘大學 === 資訊管理學系碩士班 === 99 === A reversible image watermarking approach recovers the original image from a watermarked image after extracting the embedded watermarks. This paper presents a wavelet coefficients based reversible image watermarking approach. The proposed method first calculates wavelet coefficients of the host image. Then each subimage is segmented to 88, 44 or 22 blocks according to their block structures. Then, the differences between central pixel and other pixels in each block are enlarged. At last, watermarks are embedded into LSB bits of above differences and then apply inverse wavelet transform to acquire the watermarked image. Experimental results show that the proposed variable block size method has higher capacity than conventional fixed block size method. Keywords：Reversible watermarking, Integer Wavelet Transform, Difference value adjustment