An Adaptive Watermarking Algorithm Combined with DCT and Fractal Coding
Xiaona Shen · Jisuanji fangzhen · 2008
An adaptive image watermarking algorithm combined with Discrete Cosine Transform (DCT)and fractal coding is proposed. The host image is split into non-overlapping fixed-size square blocks, which are categorized into two classes according to their collage errors obtained by performing baseline fractal coding. The blocks classification is utilized to form a feature mark of the host image and determine imbedding strengths of the watermark in distinct blocks. Arnold transform is applied to scramble both the feature mark and binary copyright symbol. The watermark is the fusion of the scrambled feature mark and a scrambled binary copyright symbol (using XOR operation). Lastly, the watermark is embedded into the middle frequency bands of DCT domains of distinct blocks by comparing the selected three coefficients. The experimental results show that the embedded watermark is invisible, and is also very robust against some image processing such as Gaussian filtering, JPEG compression and noising.