he composition of the image is nothing more than some number of bytes or string composed of string, however, one byte for each data bit is not an important degree of the same, often only two adjacent low-byte is not the same. For example: 00100110 and 00100111 represent the gradient of two different degrees of red, but on the human eye is not out to tell. Least significant bit LSB algorithm, is to take advantage of this point, to achieve image compression, or digital watermark feature.