Abstract: Information hiding in the communication spectrum became a critical task. The Visual Cryptography is a type of cryptography that allows the image to be divided into multiple numbers of shares called transparent shares and then transmission of images. The intruder hence cannot understand the distorted image and thus the data communication becomes secured. In existing methods works for color images with 8 colors and even few of them without halftone techniques. In this paper, the authors propose a method for images with 256 colors which are converted to 16 standard RGB colors format. It generates shares without compromising the resolution. The Floyd – Steinberg dithering algorithm is used to manipulate the 256 color code image to reduce it to 16 standard colors code image. The proposed method employs (2, 2) XOR-Based visual cryptography method is also used to generate shares. Decryption procedure enables secret image sharing and stacking. Although, the proposed method converts the 256 color image to 16 color code format for the share creation, the intensity of the original image is maintained. The resulting scheme gives the perfect security of the shares that are well encrypted and the visual quality of the stacked image is very good. The experimental results of the proposed method are compared with that of 8 color RGB share generation techniques.
Keywords: Visual cryptography, XOR, 16 standard color code image, Floyd – Steinberg dithering.