Data hiding by smart pair toggling for halftone images

There is growing interest in hiding data for authentication and copyright control in halftone images printed in books, newspapers and by computer printers. A previous data hiding method, the data hiding by pair-toggling (DHPT), is reasonably good but introduce considerable visual artifacts. In this paper, we analyze the sources of the artifacts in DHPT and propose an improvement by using smart pair toggling. Simulation results suggest that the proposed data hiding by smart pair-toggling (DHSPT) algorithm can hide the same amount of data while generating halftone images with considerably better visual quality than DHPT.