to import backgrounds you can only import bmp files. I am making an adventure at 640x480 at 16bit and with lots and lots of backgrounds, so i guess you can count the game is getting very big of size. Is there any way to reduce the size, or use for instance jpg?
jpgs mess up your graphics because they are 'lossy', zoom into a jpg and compare with the original image and you'll see what I mean..
AGS only imports bmp and pcx, pcx is a bit smaller because it uses fairly basic compression, bmp uses none.
Png support would be nice, it's gives the best filesizes and is lossless and supports 256 and high colour, and alpha if CJ does add that at some point.
For now, use pcx.
But remember, importing different format images (with the same size and pallete) do not help to reduce the final game's size as AGS uses it's internal format for storing all backgrounds.
-Cheers