How to convert to color formats 565 and A4R4G4B4

[Nightmare_82]

I want to use formats 565 and A4R4G4B4 in my game because it's faster and the vtd file is much smaller.
My BMPs are stored in a 24bit format and I want to convert them.
Can I do this in Delphi or do I have to convert them with a tool ?

[Nightmare_82]

I solved the problem using transparent tga's instead of bmps.
I used bmps black as the transparent color.