Recent Developments in Halftone Based Image Watermarking

In today's world, as the multimedia content is growing at an exponential rate, the security of multimedia content has become a very important issue. Nowadays, there are two major types of technologies which can provide solutions to the security problem. One is encryption and the other is watermarking. This paper presents a review on the recent trends of image watermarking with a focus on a special kind of watermarking method called halftone based image watermarking. The process of displaying an image with a lesser number of colours or grey levels is called halftoning. It is a crucial step in printing, especially when a printer can handle only a limited number of ink colours or grey levels.