[Bf-committers] Colormanagement Issue

Troy Sobotka troy.sobotka at gmail.com
Tue Sep 25 05:56:43 CEST 2012


It appears that something internally is a little wonk in the color
management system.

When loading the OpenColorIO test images such as Marci.png, the
transforms do not yield a 1:1 sRGB transform.

I've tested using ExponentTransforms as well, and no matter what
config (including the Nuke default), the higher end of the values
appears off by quite a factor.

Nuke passes the test fine, so it extends beyond the default Blender
set of OCIO config files. Further, the sRGB transform uses the Sony 1D
LUT in conjunction with an ACES matrix, which seems entirely odd. In
theory, if the default internal Blender space is intended to be sRGB /
709 primaries, only an ExponentTransform or a 1D bounded 0..1 LUT
should suffice to linearize the sRGB asset. This is tangential to the
issue however.

The reference images can be found at the OpenColorIO site at
http://code.google.com/p/opencolorio/downloads/detail?name=ocio-images.1.0v4.tgz

The simplest test is to load the Marci PNG file from the Nuke set, and
compare against any image viewer.

With respect,
TJS


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