UE sometimes unchecks sRGB when importing roughness textures


I’ve noticed that sometimes when I import roughness texture (grayscale .tga), it automatically recognizes it and unchecks the sRGB checkbox. Other times it just leaves the sRGB checkbox ON. This is mainly happening when I export the texture from Substance Designer.
Is there any metadata or something else that tells UE that the imported texture should be imported as linear (such as roughness or metallic). I’m confused how does Unreal sometimes knows to turn sRGB OFF.


Most likely it bases it off the filename suffix.

Nope, I’ve double and triple checked and the naming is the same, so there is something else going on

TGA and PNG (dunno about other formats) have an inbuilt color table mode, which allows the image to contain grayscale only. maybe that’s what UE is looking for?