Problem summary
Some OCIOs cause colour banding when viewing any shaded view with bright Lights and saturated colours.
That means that this issue appears when using any Shader, but also when just seeing a single Channel in shaded mode by activating Basic (F2) or Full (F3) Shaded Mode.
The following OCIOs are affects:
aces_1.0.3
aces_1.1
spi-vfx
aces_1.3 seems to cause it to a very small degree.
Note: This has also been reproduced with multiple customers' custom OCIO Configs.
Customer reported version
Mari 7.0v2
Customer reported platform
Windows 11
Steps to reproduce
Launch Mari and open any Project, such as the Example Project.
Create and view any Shader, such as a Principled BRDF node.
Open the Principled BRDF's Node Properties
Set the Shader's Base Color to a bright and saturated color. Alternatively, a Light's Diffuse and/or Specular settings can be set to a bright and saturated color. Note: A blueish purple seems to work the best due to it's high saturation and contrast. Gold seems to be the colour that causes this issue the least. Additionally, a shiny and metallic material isn't necessary, but it helps in visualising this issue.
In the Lights palette, set a Light's Intensity to a high value, such as 100.
Ensure that the View Transform is active.
Ensure you are using Basic or Full Shaded Mode by pressing [F2] or [F3].
Select File > Settings > Colorspace > OCIO Config and choose one of the following:
aces_1.0.3
aces_1.1
spi-vfx
aces_1.3 seems to cause it to a very small degree.
Note: This has also been reproduced with multiple customers' custom OCIO Configs.
Expected behaviour
A smooth gradient from brighter to darker areas:
Actual behaviour
Extreme color banding and artefacts:
Point Light:
Environment Light:
spi-vfx is particularly bad (point Light):
Workaround
Unknown.
Reproduced by support
This bug has been reproduced in:
Mari 7.0v2 - Windows 10, Rocky 9
Mari 6.0v3 - Windows 10
Mari 5.0v4 - Windows 10
Mari 4.8v4 - Windows 10, CentOS 7
Unable to reproduce bug in:
Mari 5.0v3 - Windows 10, CentOS 7
Mari 4.8v3 - Windows 10, CentOS 7
Earliest version tested
Mari 4.8v3/5.0v3 - This issue doesn't appear in this version and has regressed
