RGB Curves behave differently in Cycles and Eevee #62259

New Issue

Björn Eckhardt · 2019-03-06T14:33:07+01:00

Björn Eckhardt commented

2019-03-06 14:33:07 +01:00

System Information
Operating system: Win10
Graphics card: GTX1080

Blender Version
Broken: 2.80 18e5540a48

Short description of error

RGBCurves seem to adjust Values differently in Eevee and cycle.
Too imitate a Coloramp which is adjustable even inside a Nodegroup, I use two RGB curves in line (s. file): the left one adjust the dark parts, the right one the bright parts by adjusting the factor of each RGBCurves. In Cyles this works nice: adjust the dark parts to have black spots and then you can increase the brightness of the bright parts with the secon RGB curves Factor to brighten them up without loosing the black parts.
Switching to Eevee the first coloramp behaves similar, but the second one seems "add" brightness/value to the whole image. You loose the black spots again.
I'm not sure how it works in the background, but it seem in Cylces the values are multiplied and in eevee they are added. But probably I'm wrong.

Exact steps for others to reproduce the error
see file under: 20190306_BUG_RGBCurves_2.80beta.blend1

add material to cube
add noise texture, 2 RGBCurves, 1 Diffuse and connect them in this order to the Material output
left RGBCurve: set bottom left point to (0.90;0); factor to e.g. 0.15
right/second RGB Curve: set top right point to (0.05, 1), factor = 0
In cycles rendering: see patchie pattern,
increase factor of second RGB Curve: dark stays, bright spots get brighter
switch to eevee: already it looks different. play with the factor of second RGBCurve to see that the effect is very different

thx for your work :-D

**System Information** Operating system: Win10 Graphics card: GTX1080 **Blender Version** Broken: 2.80 18e5540a48b6 **Short description of error** RGBCurves seem to adjust Values differently in Eevee and cycle. Too imitate a Coloramp which is adjustable even inside a Nodegroup, I use two RGB curves in line (s. file): the left one adjust the dark parts, the right one the bright parts by adjusting the factor of each RGBCurves. In Cyles this works nice: adjust the dark parts to have black spots and then you can increase the brightness of the bright parts with the secon RGB curves Factor to brighten them up without loosing the black parts. Switching to Eevee the first coloramp behaves similar, but the second one seems "add" brightness/value to the whole image. You loose the black spots again. I'm not sure how it works in the background, but it seem in Cylces the values are multiplied and in eevee they are added. But probably I'm wrong. **Exact steps for others to reproduce the error** see file under: [20190306_BUG_RGBCurves_2.80beta.blend1](https://archive.blender.org/developer/F6773879/20190306_BUG_RGBCurves_2.80beta.blend1) 1. add material to cube 2. add noise texture, 2 RGBCurves, 1 Diffuse and connect them in this order to the Material output 3. left RGBCurve: set bottom left point to (0.90;0); factor to e.g. 0.15 4. right/second RGB Curve: set top right point to (0.05, 1), factor = 0 5. In cycles rendering: see patchie pattern, 6. increase factor of second RGB Curve: dark stays, bright spots get brighter 7. switch to eevee: already it looks different. play with the factor of second RGBCurve to see that the effect is very different thx for your work :-D

Björn Eckhardt commented

2019-03-06 14:33:07 +01:00

Added subscriber: @BjornEckhardt

Clément Foucault was assigned by Sebastian Parborg

2019-03-06 17:49:35 +01:00

blender-admin commented

2019-03-06 23:53:35 +01:00

This issue was referenced by e1a62fa1a6

This issue was referenced by e1a62fa1a61167990c4ade74b9e8b56573e18d2d

Clément Foucault commented

2019-03-07 01:38:26 +01:00

Changed status from 'Open' to: 'Resolved'

Clément Foucault closed this issue

2019-03-07 01:38:26 +01:00

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RGB Curves behave differently in Cycles and Eevee #62259