2D graphics engine/sprite library

Anonymous needs to make a 2D renderer in C that will display sprites taken from a cell-based 3D space in 2D in the style of traditional 2D RPGs (for example: http://www.jinseirpg.com/~screenshots/tests/Tales%20of%20Phantasia/top09.jpg ).

Can you suggest a sprite library to abstract from calling the low-level graphics library functions (like SDL, which is what I would use if I can't find anything neat, etc.), that runs under Linux, that would do at least truecolor sprites with color-key transparency?

Full graphics engines doing these kind of graphics I could adapt are welcome too.

Thanks!

Is the allegro library even being updated (with support for new cards, etc) this decade?