Image formats

OpenGL OpenGL: Basic Coding
1

I wonder where I can have some material to read about the image formats. I only know what’s going on in .PPM file, but I need to know more about gif, jpg, xpm, or bmp.
can anyone give me a help? thankx you very much. From Alan.

2

Take a look at http://www.wotsit.org

Nate http://nate.scuzzy.net

3

thankx a lot. but any converters from .ppm to .gif?
From Alan.