So I have seemed to have come across a bug where by the diffuse input is effecting the reflection/roughness of the material.
The best way I can explain is that I am doing a stone paved flooring. I've downloaded some textures, however the the diffuse is too dark. So I apply a colour correct to lighten the texture and I noticed in the beauty pass that the grout starts to become increasingly more reflective, even though its just the standard material setup with just a diffuse texture inputted.
I then check the reflection pass and I can see the lighter the texture becomes it then directly effects the reflection value and the material starts to become more reflective in certain areas as if I have applied a texture to give that effect.
I've now tried it with the legacy material and the effect is considerably reduced but still visible to a degree.
Am I totally misunderstanding what is going on or should be happening? I thought (outside of the "metal" shader) that the reflection/roughness etc was totally separate from the diffuse input and so it should then not matter at all whatever I put into the diffuse it should not effect the reflection properties of the material?
Apologies if I have totally misunderstood what is going on at shader level, I've just never witnessed this before.
I've attached a screenshot of a region to illustrate this. The only difference between the two is the colour correct input of a 0.2 brightness and -0.4 saturation. Same sort of effect is caused when using the Linear HDR adjustment (which is what I did before originally)