Methods of steganography, hiding information within images, and steganalysis, detecting the presence of hidden messages within images, are described in this article. The authors compare and contrast two forms of steganography, focusing mainly on techniques for transmitting secret messages, but also addressing applications such as watermarking, when the fact that there is hidden content does not need to be concealed, but it is necessary to make sure that the hidden content is not destroyed or affected by manipulations, such as compression techniques. For steganalysis, note that the focus is only on detection. The task of interpreting the content falls in the domain of cryptography. Visual and statistical methods are discussed. The authors suggest that there is an ongoing battle, a cyber-war, between those who would hide information, and those who need to detect and stop the practice. No specific instances of the use of these techniques are mentioned.

The article is excellent at providing general descriptions of approaches; listing available tools, with sources, for steganography and current methods for steganalysis; and providing references. However, there is little explanation in sufficient depth for someone unfamiliar with this topic to gain understanding. Even for least-significant-bit modification, the discussion of an example shown with a figure is not clear. The layout of the article, specifically the compressed tables and figures, does not serve its readers well.