摘要： 在基于单位块内黑白像素比率的二值图像水印算法的基础上，提出了一种改进的量化水印方案。算法在以合适的量化步长保证水印嵌入的稳健性，并大大提高了可嵌入水印的有效块数，同时使得水印改动的像素个数在一个量化步长以内，从而使得水印系统的容量、稳健性以及视觉失真等指标达到一个有效的折中。另外执行算法时无须记录水印嵌入的位置信息，保证了盲提取的要求。实验结果证明了这种用于二值图像水印算法的有效性和改进性。

关键词: 黑白像素比率；量化；鲁棒性；二值图像水印

Abstract: As an extension of the block pixel rate based watermarking method for binary images, an improved quantization based watermarking algorithm is proposed. Different quantization step can be adjusted for achieving appropriate robustness. The watermarking capacity has been increased greatly compared with the ones of classical robust binary image watermarking. Good tradeoff among different factor of watermarking system has been achieved. Experimental results show the method’s improved performance

Key words: Black white pixel rate; Quantization; Robustness; Binary image watermarking