【摘要】 针对几种现有的水印方法含水印图像视觉效果不佳的问题,提出了以下两种方案:一种是将水印与图像最高位面做异或运算来实现水印嵌入,此方案当水印位置和大小不受限制时,效果与以往的几种方法相近,但实现更加简单;另一种方法是在水印覆盖区进行像素比特移位,使水印覆盖处的高位像素下移,将水印置于最高位,以获得半透明的水印效果。对于任意的水印嵌入位置和水印大小,应用该方法得到的含水印图像不会出现亮度的跳变,且视觉效果自然。两种方法均可在不知道水印信息的情况下实现原始图像的无损恢复。更多还原

【Abstract】 To avoid poor appearance of lossless visible watermarks due to gray level flipping existence in some previous work,we propose two embedding methods capable of completely reconstructing the host image with satisfactory visual quality. The first calculates exclusive-OR between the image’s MSB plane and the binary watermark. The other method uses a bit-shift strategy to push down high bits of the mark-covered pixels,and replaces the MSB with the mark data,making the watermark semi-transparent and other image areas completely transparent. The watermark can be embedded into any position of the carrier image with any size. Both methods can losslessly reconstruct the host image without knowing the watermark information.更多还原