Self-conjugate watermarking technique for halftone images

A novel method for hiding visual patterns in a single error diffused halftone image is presented, called self-conjugate error diffusion (SCED). The hidden patterns appear on the halftone image when the halftone image is folded or is overlapped with its own rotated version. Simulation results show that the halftone images have good visual quality and the hidden pattern is clearly visible.