基于分形变换对比度因子的图像数字水印新算法

分形变换的独特原理使得必须研究针对其特点的水印算法,通过对图像分形变换压缩过程中有关参数的分析和试验,选择变换过程中值域块和其最佳匹配块之间映射关系的对比度因子参数进行调制实现水印的嵌入和提取,该算法能够在低计算复杂度下嵌入较大的水印容量而不会对图像质量产生可感知的影响,提取算法避免了水印信息不同步造成的信息丢失问题,提高了水印检测的准确度。实验结果证明了该算法的有效性。

New image watermark embedding algorithm based on fractal transformation contrast factor

It is necessary to study those watermark algorithms appropriate to the special feature of fractal transform. By analyzing related parameters in the process of image fractal transform and taking some trials, a new watermark algorithm embedding and extracting the watermark information was proposed by modulating the parameter of contrast factor which mapped the domain blocks to their best matched blocks in fractal transformation. Higher watermark capacity could be embedded into image at low algorithm complexity without having perceptible influence on the quality of the image. The extraction algorithm avoided the loss of watermark information because of the missed synchronization between original image and watermarked image, which improved the accuracy in extraction. Experiment results show the effectiveness of the algorithm.