A Hybrid Digital Image Watermarking Scheme Incorporating DWT, DFT, DCT and SVD Transformations
Digital watermarking provides copyright protection and proof of ownership by inserting watermark metadata as owner’s identity in digital documents to prevent authenticity and copyright violations. The paper introduces a new hybrid image watermarking scheme by attaching multiple copies of watermarks in carrier image. The new scheme utilizes the advantages of DWT, DFT, DCT and SVD transformations to offer stable resistance in protecting watermark contents from various external attacks. The proposed scheme uses Haar wavelet, Fourier, Onion Peel Decomposition, DCT, zigzag ordering and SVD transforms to decompose the carrier image in to four levels to maintain imperceptibility in the watermarked images. The algorithm attaches replicas of watermark frequency blocks in all frequency components of host image to provide better robustness against external deprivations in watermarked images. The proposed algorithm also provides the increased probability of extracting at least one undamaged replica of watermark even when other frequencies are damaged by external attacks. The experimental results in terms of visual analysis and quantitative metrics on different images with different experimental set up demarcate that the proposed scheme provides stable performance in generating better watermarked images. The watermark images extracted by the proposed algorithm from extremely distorted watermarked images are found to be with better visual quality than other methods used in the comparative study.