Prerequisites for

Compression Algorithms for Real Programmers
Wayner, Peter. 2000. 240 pages.
Categories: Mathematics, Steganography
I include this book because compression is almost always an important step prior to encryption for improved security and speed. Indeed, any modern crypto system that produces compressible output should be considered suspect. Also, anyone wishing to embark on stego will need to understand how their covers are compressed.
Although techy at points (i.e. Fourier stuff), the book should be consulted for concepts only, and not for developing code (even thought the title indicates otherwise). It covers standard coding theory, dictionaries, adaptive approaches, and wavelets, with respect to images, audio, and video. A nice 40 page section in the back details important compression related patents.

Recommended prerequisite books:
Either of these books:   
       
(Read review)
       
(Read review)
Suggested mathematical background in:

-  Calculus
Suggested computer language experience:

N/A