Image realization steganography with LCS based mapping

Image Realization Steganography aims in devising techniques that realize a secret message from a cover image using a suitable cover-to-secret mapping with low embedding rates. This paper presents an Image Realization Steganography technique which maps a secret image as a Longest Common Subsequence of a given cover image. The cover image being a string of high degree of randomness and a very large length as compared to the secret image, the length of the LCS between them is expected to be close to the length of the binary string equivalent of the secret image. This enables the proposed technique to realize a secret image with very little or no modification of the cover. Experimental results validate this fact strongly. The results also indicate that any given cover image can be used to realize a secret image as large as itself thereby establishing the high hiding capacity of the technique.