Steganography is the hiding of payload data within cover data. The goal of a steganographic method is to minimize the visually apparent and statistical differences between the cover data and a steganogram while maximizing the size of the payload. Current digital image steganography presents the challenge of hiding data in a digital image in a way that is robust to image manipulation and attack. Concealment of the payload data is contingent upon minimizing the apparent differences between the cover data and the stego data. There are two basic steganographic methods: Least significant bit (LSB) and transform-based. LSB steganography is one of the simplest methods. Data hidden in images using LSB steganography is highly sensitive to image alteration and vulnerable to attack. Transform based steganography is potentially more resistant to loss from image manipulation and increases the difficulty to a potential attacker. This paper describes a steganography implementation using the insignificant coefficients of a fast transform of an image for data hiding. The performance of this method using different transforms is measured and the characteristics of each transform are examined. Performance is measured by examining the payload density and its effect on image degradation. The performance of different transforms is measured on a variety of image types.
Eric A. Silva, Sos S. Agaian, "The Best Transform in the Replacement Coefficients and the Size of the Payload Relationship Sense" in Proc. IS&T Archiving 2004, 2004, pp 199 - 203, https://doi.org/10.2352/issn.2168-3204.2004.1.1.art00043