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Wrong interpretation of .EXR-Files in Compositor (compared to 2.49 and Lux)
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Description

PROBLEM:

I recently loaded some .exr-Render-result from Luxrender (lux-tonemapped .exr, not the raw data) into the Blender 2.5 Compositor to postprocess it. I was confused because the result looked strange but thought it would probably be an error in writing the .exr-File in Luxrender.

But 2.49 showed nearly the same result like Luxrender, being far away from what 2.5 displayed (see attachement for comparison: left=2.49; middle=2.5; right=Luxrender)

The minimal difference between 2.49 and Luxrender is no problem and can be corrected, but I didn't manage to correct the totally different result in 2.5.

SYSTEM:

Ubuntu 10.04 x64 (Gnome)
GeForce 9x Graphics
Intel q9300 cpu

ATTACHEMENTS:

- Comparison between different results in 2.49, 2.5 and Luxrender
- EXR-File I used for the comparison

BLENDER-VERSION:

Self-built r29122

user-config:
WITH_BF_FFTW3 = 'true'
WITH_BF_YAFRAY='false'
BF_PYTHON_VERSION = '3.1'
WITH_BF_JACK = 'true'
WITH_BF_OPENMP = 'true'
BF_BUILDINFO= 1
WITH_BF_OPENAL = 1
WITH_BF_JACK = 0
WITH_BF_SNDFILE = 0
WITH_BF_SDL = 1
WITH_BF_FFMPEG = 0
BF_FFMPEG_LIB = 'avformat avcodec avutil xvidcore ogg faac faad x264 mp3lame vorbis theora vorbisenc swscale avdevice'
WITH_BF_QUICKTIME = 0
WITH_BF_COLLADA = 0
WITH_BF_OPENEXR = 1
WITH_BF_GAMEENGINE = 1
WITH_BF_PLAYER = 0
WITH_BF_BULLET = 1
WITH_BF_INTERNATIONAL = 0
WITH_BF_RAYOPTIMIZATION = 1

Event Timeline

In this case, blender 2.49 is technically wrong.

EXR files are defined by the openEXR standard to be stored in linear colour space. Blender 2.49 did this incorrectly, not taking this into consideration. This is fixed in blender 2.5. If luxrender is storing tone-mapped, gamma corrected data in EXR files then they are doing it incorrect too, should probably report it to them.

As a note, I attached a screenshot showing djv, nuke, and blender 2.5 displaying the EXR correctly.

closing this report, thanks

Matt Ebb (broken) changed the task status from Unknown Status to Archived.Jun 2 2010, 12:52 AM

Reported to the Luxrender team, thanks.