Houdini Color Management Discussion

Hey everyone,
Changes in Settings for Houdini color management can be discussed there!

My proposal

Settings

I imagine something like this, and I’m not sure if it’s doable or not.

Display: default display
View: default view
OpenGL : Review output transform
   toggle that forces using this output transform on publishing

Each input filed should has a drop down menu that reads OCIO config path

  • Display button shows active_displays
  • View button shows active_views
  • Opengl button shows colorspaces’ names

Render Space

Houdini uses scene_linear role as render space.
I don’t know if it’s possible to override that.

File rules

I’m not sure about file rules for textures input transforms because Houdini seems to have some fixed built in file rules.

Houdini Color Management Research

This is a summary of what Houdini supports in regards to color management…

OCIO Config Path

Already implemented.

Achieved by setting OCIO before launching Houdini

Render space

Houdini uses scene_linear role as render space
I don’t know if that can be overridden without modify ocio config file

Display

Display list is the active_displays list in config file
default display hou.Color.ocio_defaultDisplay() is the first item in the active_displays list

image

Setting OCIO_ACTIVE_DISPLAYS before launching Houdini will override the active_displays list
windows example:

set OCIO_ACTIVE_DISPLAYS=ACES

View

View list is the active_views list in config file
default display hou.Color.ocio_defaultView() is the first item in the active_views list

image

Setting OCIO_ACTIVE_VIEWS before launching Houdini will override the active_views list
windows example:

set OCIO_ACTIVE_VIEWS=DCDM:sRGB

image

Input Transform Guessing

for Background images and Textures.
Houdini is checking file names for token and sets color correction accordingly,
but without them Houdini will assume that
8-bit ➝ sRGB
more than 8-bit ➝ scene_linear

Unlike Background images, Textures have few explicit color space options

ROP Output Transform

Different ROP nodes in Houdini with their color settings

  • OpenGL :support applying output transform, (Render Space ➝ scene_linear)
  • Arnold : it has an explicit parameter
  • Karma : it has an explicit parameter
  • Mantra : I didn’t find any options, I guess it uses scene_linear by default
  • Red Shift ROP : it has an explicit parameter
  • USD Render : I don’t know
  • V-Ray : it has an explicit parameter
  • RenderMan : I didn’t find any options

I don’t know if these parameters affect Render Space or they are just post render transformations.