A Visible Watermarking Scheme for Digital Images in Frequency Domain

A novel method is proposed for visible watermarking of digital image in frequency domain. The method is based on DCT modification of original image with respect to watermark image. The host image pixels are transformed into frequency coefficients as well as the watermark image pixels are also transformed into frequency coefficients using DCT. The compound mapping function is used to adjust the pixel values close to those of desired visible watermarks. Thus the watermarking is done in frequency domain using compound mapping function. One who has the watermark image and mapping function parameters only can remove the watermark. Thus it enhances the security. Experimental results demonstrate the effectiveness of the proposed approach.