Oblivious Fragile Watermarking Algorithms

Abstract

Dissertation entitled as “Oblivious Fragile Watermarking Algorithms” comprises of two watermarking algorithms for digital images. These algorithms are fragile in nature, and are based on frequency based transforms and blind. The first watermarking algorithm is based upon entropy of the sub band of an image. The sub band having highest Entropy is selected. The Singular Values of 4×4 blocks of the Sub band are modified to embed the watermark. The second algorithm is based on DWT, DCT and SVD. In this algorithm, the host image is decomposed into sub bands using the DWT. Diagonal sub bands are partitioned into the non-overlapping blocks of equal size. Each block is transformed by DCT and further SVD is applied and singular values are modified to embed the watermark. The effectiveness of the proposed algorithms is evaluated by PSNR for imperceptibility. Bit Correction Rate, Bit Error Rate, Similarity Index Modulation and Normalized correlation are used to evaluate the comparability between original and extracted watermark. The main contribution of proposed algorithms is they can be used for tempered detection and information security.