rule of thumb regaring sRGB vs linear colors

[Millionviews]

@Maximum-Dev;535593

sRGB should be checked for Diffuse/Albedo and unchecked for Roughness/Metallic/Normal/Specular maps.

Basically when you import a texture it’d end up looking exactly the same when you look at it with Unlit view mode. Can you post a comparison so we can see better?

<- it is basically toggling sRGB for diffuse textures doesn’t change anything in the viewport, only in the texture editor. It just looks like the texture in the viewport always is sRGB enabled. (which is confusing, because I just uncheck sRGB for diffuse in the texture preview window)

@richardek;535931

sRGB is used for maximizing quality of a limited 8-bit image. It lifts the color values of the more important dark parts of the image before it gets saved. Because our eyes is more sensitive to differences in darker colors than brighter, the darker parts gets more room in the small 0-255 value space. When you open a sRGB file the values gets lowered again to look like they did before you saved the file.
The Roughness/Metallic/Normal/Specular is more for mathematical use inside the engine and not to be used to looked at directly like a Diffuse map. And you want to save evenly distributed values (linear) without the gamma shifting sRGB does. In linear the brighter values are as important as the dark ones.

ok, the whole sRGB thing makes sense now…but now I am wondering, and maybe this is not the correct place to ask but the following:
when I create textures in Substance Designer, all textures kinda looks exact the way I expect them to be. I expect when i turn off sRGB in SD the texture should appear darker but they don’t… they look lighter instead.
Back to unreal…when I create a dark stone in SD (with sRGB enabled), import that one in UE and toggle sRGB on and off I can see clearly difference in the texture preview window. Without sRGB (!) in the texture preview window the image looks the same as in SD while in SD sRGB has been turned on whole the time…?!?

UE4 sRGB off = SD sRGB on = ?!?

Shouldn’t both images not look the same, because sRGB has been on in both engines?!
Regards! T

edit: just tested a quick workflow…when I put a ‘convert to linear’ node for the base color in SD, the image becomes darker. When I import that image in UE4 and leave sRGB enabled it looks exact the way I want it to be. Still…love to hear some thoughts on above.