A novel spatially based watermarking technique with prediction-based recovery

A novel spatial watermarking scheme that is highly robust is proposed. The embedding is achieved through a process similar to direct sequence spread spectrum techniques. Integral to this is modulation according to a perceptual classification of the cover pixels. The classifier is based on the Sobel gradient operator and identifies the cover pixel region as either constant, edge, pseudo-constant, texture, or mixed. Recovery of the watermark does not require the original image and is achieved through a simple prediction process based on an adaptive threshold.