Books:

1. A.K.Jain, Fundamentals of Digital Image Processing, Prentice-Hall, 1989.
2. Rafael C. Gonzalez, Digital Image Processing, Second Ed., Pearson Education,2004.
3. Bernd Jahne, Digital Image Processing, 5th revised and extended edition,2002.
4. Tinku Acharya, Image Processing Principles and Applications,2005.
5. Dwayne PhillipsImage, Processing in C, Second Edition, 2000.

Online Refrences:

1. http://www.viz.tamu.edu/faculty/parke/ends489f00/notes/sec1_8.html
2. http://www.mathworks.com/help/toolbox/images/f7-12915.html