Visual Cryptography Using Space Filling Curve Ordered Dithering With Adaptive Clustering

In this paper, the authors investigate the problem of varying the size of dots in the digital half toning processes. The reproduction of grey scale images in bi-level graphic displays is achieved through a process called half toning. Given a grey scale image it consists in generating a binary image which causes the impression of continuous variation. This process can be analog or digital. Analog half toning is done using photographic means to generate high contrast halftone screens. Digital half toning is done using a technique called dithering to determine the binary state of the elements of the output image.