There were some abstractions inside `IMB_transform` implementation
that were kinda getting in the way. I want to speed up Subsampled3x3
filtering by reformulating the math being done, but that needs to
sample byte images while storing intermediate result as a float -- but
the whole `Pixel`, `PixelPointer` et al. machinery was not quite prepared
to deal with that. Feels like those helper classes do not achieve much,
just make the code longer.
So remove them (`Pixel`, `PixelPointer`, `ChannelConverter` etc.) and
use simple functions. Now the code is more straightforward (IMHO) and
270 lines shorter (40% of the whole file!), and allows me to do the
follow-up optimization easier.
No functional changes.
Pull Request: https://projects.blender.org/blender/blender/pulls/117182
2391338ba0