关键词: 彩色图像, 数字水印, 空间域, 均值关系

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