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International Journal of

Recent Trends in Engineering

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International Journal of Recent Trends in Engineering (IJRTE)

ISSN 1797-9617

Volume 1, Number 1, May 2009

Issue on Computer Science

Page(s): 468-471

Achieving Optimal Contrast in Visual Cryptography Schemes without Pixel Expansion

Thomas Monoth and Babu Anto P

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In this paper we present visual cryptography scheme to encode a black and white image into the same size shares as the secret image. In addition, an improved method for the generation of shares is proposed using additional matrix. Visual cryptography method for encrypting printed texts, handwritten notes, and pictures are done in a perfectly secure way, and decoding these data with the human visual system. The contrast is the most important parameter in visual cryptography. Usually, the reconstructed secret image will be darker than the background of the original secret image. The proposed scheme achieves better contrast and reduces the noise in the reconstructed secret image without adding any computational complexity. In this technique the number of white pixels in the reconstructed secret image can be improve 50% or more compare to the existing method.

Index Terms

visual cryptography, visual secret sharing, secret sharing, cryptography, optimal contrast, pixel expansion

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