if your picture contains less then 256 colors, GIF is for you!
but if you have rather large pictures or BG, you might try to use jpeg
and if you need to have good quality, might be with transparency, might be big as well, you need to use PNG for sure!
I will do the same thing for an image large of 256x256.
*a while goes*
well, my program doesn't support them all either, but here is what I have:
Jpeg: 31KB (Not so good quality)
Bmp: 193KB
Gif: 16KB (bad quality of course)
Png: 54KB (The best choice for the best quality images with one of the smallest size!)
Tga: 192KB (About same size as bmp...)
Xpm: 624KB (O,,o)
NOTE:
All images were saved using this setting: 256x256x16bit (Except for GIF only supporting up to 256 colors)
Here is the original image:
- Original file