Steganography is an important branch of information hiding, and has been widely studied and applied in information security. Therefore, it is also very necessary to study corresponding stegananlysis. According to the basic principles of LSB steganography of images, embedding hidden secret messages into a cover image, and respectively comparing and analysing the differences between the cover image histogram and the histograms of the stego-images with different embedding rates, researches find that the histogram of the stego-image obviously shows abnormal when embedding rate reaches some degree, though the cover image and its corresponding stego-image are not obviously different in human vision. The histogram of the cover image without embedding hidden messages is generally normal. If we find that the histogram of an image is obviously abnormal, then it is very possible that the image hid secret messages. Steganography often destroys some original and basic characteristics of a cover image. Steganalysis researches are to detect and find differences between some kindred properties of the cover image and its corresponding stego-image, and to further confirm the existence and the amount of hidden information.
