Paper title:

Visual cryptography for gray-level image using adaptive order dither technique

Published in: Issue 2, (Vol. 3) / 2009
Publishing date: 2009-10-20
Pages: 60-65
Author(s): Nagaraj V. Dharwadkar, Amberker B.B., Joshi Sushil Raj
Abstract. Visual cryptography Scheme (VCS), an emerging cryptography technology, uses the characteristics of human vision to decrypt encrypted images without requirement of complex computation. Naor and Shamir proposed the basic model of visual cryptography for binary images. Since then researchers have published many papers related to this model, but only few papers have been published related to gray-level images. In this paper, a new technique for visual cryptography of gray-level image is proposed, which uses first adaptive order dither technique to convert a given gray level image into an approximate binary image. Then, the existing visual cryptography scheme for binary image is applied to accomplish creation of shares. The overall effect of the proposed method is the achievement of visual encryption and decryption functions for gray-level images, where the quality of decrypted image is better compared to the decrypted image obtained by VCS using Space-filling curve order dither technique. This is shown by experimental results based on the objective measurement technique.
Keywords: VCS, HVS, SFCOD, Halftone, Dithering.

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