10-22-2023, 05:22 PM
From your edit you've found a solution, but I'm posting this explanation anyway.
The premise here is that normal maps don't actually need the blue data saved in the image, because you can just recreate it from the red and green (since the idea is that it's a unit vector). The BC5 format is designed specifically for this, and any competent extractor will offer the option to auto-calculate the blue channel for it when extracting. And if it doesn't, there's probably some tool out there that will do the conversion for you.
The premise here is that normal maps don't actually need the blue data saved in the image, because you can just recreate it from the red and green (since the idea is that it's a unit vector). The BC5 format is designed specifically for this, and any competent extractor will offer the option to auto-calculate the blue channel for it when extracting. And if it doesn't, there's probably some tool out there that will do the conversion for you.