What are spatial watermarks ? If they are perceptually based, are they always robust ?
Spatial domain, additive watermarking is the same as additive watermarking in any domain that is a linear transformation of the spatial domain, e.g. Fourier, block DCT, wavelet, etc. It usually means that someone has created a watermark pattern that has the same dimensions as the original image and has added the watermark pattern to the image. The watermark pattern can be modified by, or even created with a perceptual analysis of the original image. This does not directly effect the robustness. Perceptual modeling usually improves the fidelity so that means, for the same fidelity impact, you might be able to embed a “stronger” watermark. Often, “stronger” implies more robust, but not always. The following papers are recommend to see that “stronger” does not always mean more robust. • M.L. Miller, I.J. Cox, and J.A.
