In this thesis, we investigate two topics for halftone image: (1) Inverse halftoning and (2) Watermarking for halftone images....[ Read more ]

In this thesis, we investigate two topics for halftone image: (1) Inverse halftoning and (2) Watermarking for halftone images.

Halftoning is a process to change multi-tone images into 2 tone images, which look like the original multi-tone images when viewed from a distance. Halftone images are widely used in the printing of books, magazines, newspapers and in computer printers, which are very common in our daily lives. Inverse halftoning is a process to recover the multi-tone images from halftone images. Since halftoning is not an invertible process, there is no clear best or unique approach for inverse halftoning. In this thesis, we propose a low complexity, high quality Fast Adaptive-spatial-varying Filtering (F-AF) for inverse halftoning, which is robust to different kinds of halftone images.

Watermarking is a process that can embed some invisible data called watermark into an image. For halftone images, it is often desirable to hide certain invisible data within the halftone images such as company identity, owner information, creation date and time and other information for copyright protection and authentication purposes. In this thesis, we propose two series of watermarking algorithms for halftone images. They are Data Hiding Toggling and Data Hiding Halftoning.