Yellow/Green Normal Maps

I hope I chose the correct forum thread here; the problem isn’t directly linked with Blender, but could be solved with it maybe, I’m not quite sure. :face_with_raised_eyebrow:

So I’m currently extracting models from a video game in order to work on a short animation in Blender. The extraction and conversion worked quite well, I got a bunch of .obj files together with their .dds texture files.

The game’s models use a lot of Normal Mapping for creating geometry illusions, and I’m used to either Black/White height maps (aka “Bump Maps”) or the purple/blue, usually used Normal Maps.

Interestingly though, the .dds maps are yellowish/green with an alpha channel on it; has anybody any idea on how to convert those?
I googled “yellowish/green normal maps” with different title formations several times now, and I couldn’t even find this type of maps.

So I tried to invert the color, to extract the alpha channel and invert, to lay black/white color underneath and invert, but none of that works, for it’s either too light or dark (and therefore ruins the whole geometry illusion). I would simply ignore the “slight” color differences, but they have a huge impact on the actual geometry illusion, so that isn’t an option, sadly. And converting those maps has to be possible, for I found a program using some of the models I’m trying to convert and managed to get usual Normal Maps of the ingame models.

I’ll link an image comparison below for you to see what I mean (the actual Normal Map is taken from that one program I noted above; I don’t have them for every model I want to use, of course). All of the ingame yellow/greenish conversion tests feature a noticeable seam in the middle of the mesh, as well as visible geometry (flat shading) often.


(Link with actual alpha channel: https://drive.google.com/open?id=1M21j3PaXq3aLNLJVCmOYoDZvcInDnwCF )

This is a compressed normal map. Try dropping the alpha channel into the red channel. Or upload the actual normal map file.

I managed to get the correct result by switching color channels around. Thanks for the input!

Glad you got it sorted. When games are shipped the normal map compression is baked in. The blue channel is either dropped or used as a packer channel on import to engine.