I'm talking about removing background color of spritesheets (limited to 256 colors), not the high resolution or 3D models.
What I meant by "sprites" are the retro type graphics like Mario Bros or Pokemon GameBoy sprites, not the sprite object type in C2.
What I used to do was use Photoshop's Indexed color mode and select the spritesheet color as the last (bottomright box) so Photoshop will know that color is the background color. I know how to do it in GIMP too (using Alpha) but I was just asking for a lightweight software that's easy on memory
Already tried clippingmagic before I posted here.
I'll try to post a screenshot of what exactly I'm talking about (in Photoshop) later.