BMP Files in c

[Quik]

Hey,could anyone help me out in converting a image to its negative i.e. create a negative image of the input bitmap file (in c)
i`m new to image processing..suggest some link that gives some info on bmp loader etc.. and it would be of great help if someone could suggest a algorithm..

[Albatross]

http://www.sfml-dev.org/
See what you can do with that.

-Albatross

P.S.-There was no need to make two other clones of this thread in "Lounge".

[Quik]

firstly, i didn`t realize i was posting it on lounge..
secondly, i want a brief algorithm first so that i know how to go about it .. would appreciate your help and thnx for the site it`s useful ;)