为了可靠地对白色像素较多的灰度图象进行保护，提出了一种稳健性好的数字图象盲水印算法，该算法尤其对白色像素较多的灰度图象稳健性较强.该算法是基于原始图象的傅立叶变换，将调制后的水印信息依次加入到某些固定位置的幅值谱上.该算法具有以下特点 :(1)对不同的图象，嵌入水印的强度不同，对白色像素较多的图象嵌入水印的强度较大，这样可以使透明性和鲁棒性达到较好的统一 ;(2 )选择频域幅值谱，使嵌入水印信息的相互位置之间保持一定距离，以便减少不同幅值之间的干扰 ;(3)对同一幅图象而言，嵌入水印和提取水印的参数不同，而且检测的区域大于嵌入的区域，这样就可能排除由于图象空频变换而造成的能量损失 ;(4)在提取水印时，通过对检测图象加入随机序列来补充由存储造成的丢失信息.实验表明，该算法不仅具有较强的鲁棒性，对裁剪、噪声、压缩、涂改、平移抵抗性较强，并且复杂度较低，实用性较强.

The paper proposes a valid blind image-watermarking algorithm. Especially, the algorithm is also effective for some kind of images that have a lot of white pixels. These special images usually can produce a lot of overflows after being embedded the watermark. Furthermore, the magnitudes of these special images are bigger than usual images in some positions after being transformed. So, these images are hard to get the balance between robustness and transparentness. The method is based on Fourier (FFT) transform. The algorithm embeds the watermarking signal modulated on some fix positions that keep some distance from each other. Furthermore, the paper adds some decimals to the image-signed and choose some interrelated regions to extract the watermarking info during detecting, which reducing some data damage caused by saving the image-signed. Experimental results and attack analysis are given. For different images, the algorithm embeds different parameters during embedding watermarks in order to identify watermarks clearly. For the same image, the parameter of extracting is smaller than the one of extracting and the area of extracting is bigger than the one of embedding. The experiments show that it is transparent, robust, accurate and cost-efficient. Especially, the algorithm is strong to withstand the attacks of cutting, noising, compression, erasing and translation.