An improved algorithm of watermark preprocessing based on Arnold transformation and chaotic map

Abstract

One of the main purposes of watermark preprocessing is to improve the robustness and security of the watermark. In this paper we proposed an improved image encryption algorithm, which combines position scrambling and gray scrambling. In order to achieve image location scrambling, first of all, the image is divided to even blocks, and the sub-blocks are scrambled according to Arnold transform. Then all of the pixels of each sub-block are scrambled by the proposed algorithm based on Logistic chaotic map. Finally, all of the Pixels are redistributed and scrambled totally. Basing on image location scrambling, it makes use of Logistic chaotic map and multi-dimensional Arnold transformation, image gray scrambling is attained. By histogram analysis, key sensitivity analysis and correlation analysis of adjacent pixels of the results of the simulation, indicating that the scrambling effect of the improved algorithm is good, and the key space is more larger.