@Ultim, Pinterf,
Sounds great. Once high bit-depth planar RGB is also supported, it's possible to load and save high bit-depth images using DevIL (sadly DevIL supports only interleaved and not planar RGB formats).
I implemented such a thing a long time ago:
https://sourceforge.net/p/avisynth2/patches/6/ At least i got it working
@jackoneill, i see what you mean. I thought it would be a good idea to have a consistent naming of those conversions. I guess better would be ConvertToY400.