Intrusive and non-intrusive watermarking

"Can we watermark without perturbing an image?" We present the salient results of an investigation carried out to find an answer to this question. We judge candidate watermarking schemes based on transparency, robustness, capacity and non-invertibility, together referred to as the governing factors. We refer to schemes that embed by perturbing an image as intrusive schemes, and those which claim to embed without perturbing an image as non-intrusive schemes. We discover that it is only to ensure non-invertibility that an image needs to be perturbed in order to be watermarked. We propose a watermarking framework designed such that any watermarking scheme which embeds by adhering to the rules of the framework carries with it the positive aspects of non-intrusive embedding and at the same time is non-invertible.