Abstract
In this chapter, the author describes the various substitution-based image steganography techniques. Basically, there are four categories of substitution techniques: (1) least significant bit (LSB) substitution, (2) LSB array-based substitution, (3) group of bits substitution (GBS), and (4) adaptive LSB substitution. The LSB substitution-based techniques are very much insecure (detectable by RS analysis), so LSB array, GBS, and adaptive LSB substitution techniques are proposed in literature. If substitution principle is used in a steganography technique, then it must be evaluated by RS analysis.