Client-Side Watermarking for Images With Solid-Color Backgrounds

The ever-growing popularity of image sharing underscores the claim for copyright protection. Digital watermarking plays a pivotal role in combating illegal redistribution and safeguarding copyright. This methodology includes two embedding modes, namely owner-side and client-side embedding, with the latter having an advantage in terms of owner-side efficiency. However, all current client-side watermarking schemes overlook the applicability to images with solid-color backgrounds. Building upon existing researches, this letter uses the lookup table method to realize the client-side embedding of watermarking, and puts forward two schemes specifically tailored for images with solid-color backgrounds. Both two schemes achieve global encryption while successfully limiting the residual watermark effects after decryption to the subject matter of the image. Separately, one scheme adopts the principle of spread spectrum, while the other relies on the principle of spread transform dither modulation. These two schemes exhibit distinct performance trade-offs, and through experimental verification, we demonstrate their decent visual performance, robustness, and efficiency.