Anyone know a good program for converting an image with transparency to 16-bit colour without dithering it? We're trying to compress our image data down past a certain threshold and 16-bit colour works, but the dithering applied by our texture generating tool (PVR) makes it look like trash. The version of Photoshop we have apparently doesn't even support 16-bit colour anymore (wtf). If the Gimp or whatever can just open the file, convert to 16-bit colour without dithering, and then save a 32-bit PNG, that would probably work, since I imagine the colours produced even in 320bit wouldn't be prone to dithering in 16-bit. Any suggestions would be great; thanks.

EDIT: By 16-bit I mean RGBA4444 ....

I considered that, and am still considering it, but I don't have Allegro installed here and I don't know how easy it is to work with the PNG file format. I was hoping for a quicker option.

Anyway, I seem to have found one; turns out an older version of the PVR tool defaults to no dithering when compressing to 4444 while the new version doesn't even give me an option. So older version it is.

You might be able to save the array to a TGA file (RLE compressed as you will) with some sort of flag in the "developers section" to specify that it's in the 4444 format.