idin ata in Color alftone Ima es usin Error iffusion with onlinear hresholdin

Halftoning is the process of representing a gray-level image with a binary image. Image data hiding is the hiding of invisible patterns in an image without degrading its visual quality. The error diffusion with nonlinear thresholding (EDNT) method embeds binary patterns or textures in a black and white halftone image. In this paper we propose a method called CEDNT to embed hidden data in a color halftone image as a generalization of EDNT. The hidden pattern can be extracted by overlaying the three RGB components of original and watermarked halftone images and then combining them into the resultant image. It can also be visualized by means of a simple XNOR operation on each of three RGB components of watermarked and original halftone images. The main advantage of this method is that the intensity of the extracted pattern can be adjusted by means of three algorithms. So in any application by changing these parameters we can make a balance between intensity of the extracted pattern and the visual quality of watermarked images