# Visual Cryptography Essay

1041 Words5 Pages
In order for the benchmarking scheme to be properly developed and executed, a developer needs to have an awareness of the history of Visual Cryptography. The developer also needs an understanding of the underlying concepts of Visual Cryptography and how they are used to generate shares of binary images. Recently, Visual Cryptography has been extended to accommodate shares of gray and color images, further extending its capabilities and versatility. This understanding of Visual Cryptography is necessary to allow an objective comparison of all the different types of algorithms. 1.5. PROOF OF CONCEPT - BINARY IMAGES: The process behind Visual Cryptography allows messages to be contained in seemingly random shares. The generation of these…show more content…
2 Issue 6group occurring. A share generation scheme corresponding to k = 2 and n = 2. This is applied to a binary image by assigning the corresponding sub-pixel grouping to the pixels throughout the image. This results in two random shares where the message cannot be identified. The mathematical proof of this scheme and its perfect encryption are shown in the original paper by Naor and Shamir \Visual Cryptography”. 1.6 EXTENSION TO GRAY AND COLOR IMAGES: The process of Visual Cryptography, as developed through the original algorithm [12], was designed to be used with binary images. This is illustrated from the nature of the shares and the encryption process documented previously. If the secret messages being encoded contain text or binary images, the process shown in the original algorithm works well. However, the world is not composed of solely black and white pixels. With the increasing production of images in the digital age, gray and colour images have a pressing need for encryption and protection as much, or more, as binary images. 1.6.1 GRAY IMAGES: The development of an algorithm to encrypt binary images, they were also aware of the eventual need to encrypt gray and colour images. In the last section of their paper, they proposed a technique which involved printing each of the pixels in an image as half black - half white circles. This allowed the rotation angle of the corresponding circles to vary