Abstract: This paper presents a new perceptual digital watermarking scheme based on human vision system, discrete wavelet transform and orthogonal vector. The original gray image is first divided into 8×8 blocks, and then 8×8 blocks are permuted. A 1level digital wavelet transform (DWT) is applied to each 8×8 block. Each watermark bit is modulated by orthogonal vector, then the watermark is added to the original image.Finally the IDWT is performed to form the watermarked image. In the watermarking detection process, two detection algorithms are proposed. By hypothetical testing, the watermark can be extracted exactly. The experimental results show that the proposed technique successfully survives image processing operations, image cropping, and the Joint Photographic Experts Group (JPEG) lossy compression. Especially, the scheme is robust towards image sharping and image enhancement.

Key words: digital watermarking, digital wavelet transform, orthogonal vector, data hiding