Robust watermarking using orthonormal code spreading in the DWT domain [image watermarking]

Digital watermarking is a technique that aims at hiding a message signal in a multimedia signal for copyright claim, authentication, device control, or broadcast monitoring, etc. In this paper, we focus on embedding watermarks into still images. We propose a blind watermarking scheme using orthonormal code spreading in the discrete wavelet transform (DWT) domain of an image. It can support grayscale images and color images. For fighting some attacks, including row/column removal, cropping, and image rotation etc., we embed attack-detection messages in the edge lines of the watermarked image. An explicit quantitative relationship regarding the trade-off between the watermark bit error rate (WBER) and the peak signal-to-noise ratio (PSNR) for the proposed scheme is derived.