Watermarking in Halftone Images with Parity-Matched Error Diffusion
A halftone watermarking technique of high capacity, robustness, and capacity flexibility is presented in this paper. This parity-matched error diffusion (PMEDF) method is capable of achieving an embedded capacity as high as 6.25% to 25% with good image quality and without the original image as the reference to decode the watermark. As the experimental results demonstrated, this technique is able to guard against degradation due to cropping, tampering, and printed-and-scanned process in error-diffused halftone images.