Date Added: Jul 2011
Steganography is the art of secret communication. Its purpose is to hide the very presence of communication as opposed to cryptography whose goal is to make communication unintelligible to those who do not possess the right keys. This paper shows that most of the steganographic systems proposed during the past decades usually substitute the insignificant parts of the image with the secret message. However, these systems don't pay attention to these parts, and the original image is distorted by some small amount of noise due the data embedding itself. This noise could reveal the existence of secret message and hence change the statistical profile of the cover image significantly.