Hmmm... I don't know. We obviously must have done it at some point, in order to get those 16-bit splashes into UE, but it was so long ago, I just don't remember . I'll look into it, though.
I can only get 16 bit iffs to look correct when I use the command line program (bmp2iff.exe I think?) instead of textconv. Maybe that's what UE did too?
Yes, that's right. It's all coming back to me now. You can use texconv for all the standard 256-colour stuff, but for more complicated things like 16-bit colour or 8-bit MATs with transparency, use HCl's BMP tools.
. I'll look into it, though.