Abstract: A blind watermark scheme of color image in spatial domain is presented.The luminance component Y of color image in YUV color space is partitioned into image blocks with 4×4 size，and those blocks are divided orderly into groups according which every two neighboring image blocks become a group.Next，the watermark embedding is realized by applying the greater and lesser relationship of mean luminance between two neighboring blocks in selected image groups.On other hand，the watermark extraction is achieved through judging the relationship between two neighboring blocks.Experimental results show that the proposed method has good performance and the robustness to resist common attacks such as JPEG，rotation，scaling，sharpening and low pass filtering，which is superior to other several methods.

Key words: color image, digital watermark, spatial domain, mean relationship

摘要： 提出一种空间域彩色图像的盲水印方法。该方法首先对YUV彩色空间中图像的亮度分量Y进行4×4分块，按每两个相邻图像块为一组对其分组。然后从挑选的图像块组中利用相邻图像块的亮度均值间的大小关系来实现水印的嵌入。而水印的提取是通过判别相邻两个图像块亮度均值间的大小关系来完成。该方法具有其实现简单、计算代价小和速度快的特点，同时实验结果表明在对抗诸如JPEG压缩、旋转、缩放、锐化和低通滤波等攻击有比其他几种方法有更好的性能和鲁棒性。

关键词: 彩色图像, 数字水印, 空间域, 均值关系