关键词: 局部质量评价, 不可感知性, 鲁棒性, 扩频水印

Abstract: To seek the good tradeoff between robustness and unobtrusiveness, the cover data is divided into nonoverlapping blocks and an independent distortion situation is assigned to each block, which is called localized quality evaluation. Two specific implementations applying the Signal to Noise Ratio and Watson's visual model as the quality metrics are respectively achieved in the sense of maximizing the detection value. And the corresponding upper limits are derived under the given distortion constraints. Then, some practical adjustment strategies of those relative parameters are provided. The approach also introduces an improved linear correlation detector using side information and analyzes its performance mathematically. A lot of experimental results show the presented schemes obtain very significant performance improvement in terms of image transparency and robustness.

Key words: localized perceptual quality evaluation, imperceptibility, robustness, spread spectrum watermarking