An Approach for Grey Scale Image in Visual Cryptography Using Error Diffusion Method

Visual cryptography is a special encryption or cryptography technique used for securing the visual information like text, pictures etc to be performed in such a way that their decryption can be performed by human visual system. The basic idea of visual cryptography is based on the process in which the original image is firstly converted into halftone image which is a binary image and then it is divided into several parts called as shares. Secondly these shares are distributed among different concerned participants and at last to decrypt that images the images must be stacked onto each other to get the original image. At first there are various measures on which performance of visual cryptography schemes depends such as pixel expansion, visual quality, image quality, contrast, security, quality of shares, size and computational complexity. In this paper half toning by error diffusion is used to make a better quality halftone image and we developed a new modified process and an algorithm used to develop a better quality halftone image.