[Openexr-user] CTL questions

[gga]

Hi, Florian.

I'm integrating CTL into my applications and I have some questions
regarding the demo programs and its OpenEXR interaction.

Currently, the demo programs define CTL_DISPLAY_WHITE_LUMINANCE and
CTL_DISPLAY_SURROUND_LUMINANCE, which are then shuffled into the OpenEXR
environment header as the attributes "displayWhiteLuminance" and
"displaySurroundLuminance".
Now, as far as I can tell, these two attributes are currently a NO-OP in
any of the demo programs and the CTL library.   Is this on purpose?

The chromaticities attribute, on the other hand, works properly.
However, with the demo programs, I am unable to understand what settings
would produce a simple pass-thru (ie. no color transform just as, say,
the old exrdisplay would do with gamma and gain at 1.0 and no
defogging).  I expected that setting a gamma of 1.0, Rec
709.chromacities and using the default .ctl programs would achieve this,
but what I obtain is an image that is almost a 0.5 stop darker.  I
expect this is some user error on my side, but I'm not sure what it is
exactly.

The demo programs seem to construct a 3d Lut of 64x64x64 half values.
Is there any particular advantage to using a half 3d texture in this
case (as opposed to a full float texture)?



-- 
Gonzalo Garramuño
address@hidden

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