Color corrections and blend modes don't work with projected roughness?

[Steve5D7C]

Am I missing something, or do neither blend modes or levels work on a layer that has only roughness applied via a texture?

I have some white lettering that's being 3D projected, via a PNG with transparency.

If I duplicate this layer and plug it into a roughness only fill layer, I get the expected white values in the roughness channel.

However, if I want this value to be black, I should be able to color correct only this layer somehow, such as by applying a levels effect with "invert" checked (to get a black roughness value). Or, setting the blend mode on the roughness channel on the layer to "subtract" should have a similar effect.

Neither seems to work and my roughness values on the lettering stay white. It's as if the roughness channel is continuing to read values directly from the texture and ignoring any downstream processes.

???

[Steve5D7C]

Never mind, although it still doesn't make sense to me that setting the roughness channel to "subtract" doesn't work, I realized I needed to set the affected channel in the levels effect to roughness, then invert. This got me the result I wanted.

[davescm]

Subtract blend mode will work for the roughness channel (same as any other channel) but only if there is something in the layer(s) below, for that channel, to subtract from. If the layers below are empty, then it will have no effect.

I've just tested in v8.1.3 to make sure nothing had changed.

Dave

[Steve5D7C]

Yes, that's pretty obvious. There were layers with roughness channels below the one I was setting to subtract. It didn't work.

[davescm]

Strange, I can't replicate that issue here.

As a test, to make sure we are doing the same thing, can you try it with a white fill on the roughness channel of the layer below and a white or gradient fill on the roughness channel of the layer set to subtract and post a screenshot set to show the roughness in the 3D and 2D views, and with the layers panel set to show the roughness channel.

Dave