Only RGB channels from the RGBA layer are affected - the alpha is not and this
has been the case for several years now in Nuke.
This is the correct and desired behaviour, though admittedly seems strange at
first.
Any other embedded layers in an exr file are (or should be) treated as linear
and no conversion is applied.
Testing your script though I am not seeing the purple you are seeing. RGB is
changed but Alpha and reflection are identical.
Nuke 6.3v8 -MacOSX Lion
Howard
>________________________________
> From: "[email protected]" <[email protected]>
>To: [email protected]
>Sent: Thursday, 5 July 2012, 21:45
>Subject: Re: [Nuke-users] 6.3v8 OCIO display lut
>
>
>
>I understand that the alpha has the purpose of defining transparency
values however it should be treated like any other channel/layer in the
software. Especially as the view transform is applied to all layers
(when using 'all') some of which are meant for color some not such as
diffuse vs velocity yet they're both just channels as far a Nuke is
concerned.
>
>I guess it just seems pretty strange/undesirable to me to have a value
of 0.5 in the RGB and 0.5 in the Alpha appear a different shade to
each other in the viewer.
>
>I'm also seeing a bug where the viewer lut is applying to only the Red
and Blue channels of my other layers. Making all the other layers in my
renders appear purple. I have tested this on multiple files, multiple
machines and multiple scripts with the same result from the OCIO
display transform. I have attached a couple screen grabs of a test just
using a ramp to see clearly and only changing the view transform.
>
>I can confirm that all of the channels and layers have the exact same
data values yet you can see how they appear. In the test attached im
using the OCIOdisplay node just to show them all at once however this
is the same results as switching between luts in the viewProcess and
viewing the layers directly.
>
>Anyone else experiencing this?
>
>Regards
>
>Andrew
>
>
>
>–––––––– MIRADA
Purveyors of Handmade Storytelling,
Since 2010 4235 Redwood Avenue
Los Angeles, CA 90066
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independent of this message.
>On 07/05/2012 09:15 AM, Sean Looper wrote:
>Andrew,
>>
>>
>>Another reason is that OCIO defines LUTs for RGB channels only.
It would be difficult in many cases and impossible in others to
determine which transformation to apply to the alpha channel data.
Aside from the reasons why you wouldn't want a transform applied to
non-image data (i.e. alpha, depth, uv, etc), when you look at
transforms that contain cross-talk between channels, even attempting to
derive a 1D LUT from a 3D one for the purpose of applying to a data
channel would produce unreliable results.
>>
>>
>>-sean
>>
>>
>>
>>
>>
>>On Wed, Jul 4, 2012 at 5:45 PM, randmin <[email protected]> wrote:
>>
>>Because usually the alpha is
nothing more then transparency values so it is represented in a way
that best resembles how it is applied to the data. You alpha isn't
getting and CC where as your rgb and other channels have to have a
proper color look to be blended. (alpha blending is linear multi. why
would you want it to do anything else?)
>>>
>>>
>>>Randy
>>>
>>>
>>>On Jul 3, 2012, at 4:54 PM, [email protected] wrote:
>>>
>>>So using the OCIODisplay
now with the viewerProcess set to none does
give me the same result as using selections in the viewerProcess as it
should and yes the transforms are applied to all layers and channels
except the alpha.
>>>>
>>>>This is a desired result you say? Why would you want your alpha not
represented the same as everything else?
>>>>
>>>>Andrew
>>>>
>>>>––––––––
>>>>
>>>>MIRADA
Purveyors of Handmade Storytelling,
Since 2010 4235 Redwood Avenue
Los Angeles, CA 90066
+1 424 216 7470 mirada.com Please consider the environment before printing this
email. This communication is confidential and may contain legally privileged
information related to Mirada. If you are not the named recipient, please
contact us immediately and delete this message and attachments. You must not
copy, use or disclose this communication, or any attachments or information in
it, without our prior consent. All opinions, conclusions and other information
expressed in this message not of an official nature shall not be deemed as
given or endorsed by Mirada unless otherwise indicated by an authorized
representative independent of this message.
>>>>On 07/03/2012 10:52 AM, Sean Looper wrote:
>>>>The OCIO Viewer LUTs are just OCIODisplay
nodes. Try
inserting an OCIODisplay node in your graph and viewing from there with
your Viewer LUT set to "None". Pick an obvious transform from the "view
transform" knob and cycle the "layer" knob through your various layers.
You *should* see the transform applied to whichever layer you select.
What you shouldn't see is the transform being applied to the alpha
channels.
>>>>>
>>>>>
>>>>>Let us know if you see anything different than the above.
>>>>>
>>>>>
>>>>>-sean
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>On Mon, Jul 2, 2012 at 3:58 PM, <[email protected]> wrote:
>>>>>
>>>>>Hey
Sean,
>>>>>>
>>>>>>I'm using the "rec709 (default)" from the viewer lut pulldown though
srgb has the same issue and I dont have any other view luts currently
installed. We have a custom OCIO config originating from opencolorio.org
>>>>>>
>>>>>>A quick and clear test is to make an RGBA ramp and compare the RGB and
the A through different viewer luts and none.
>>>>>>
>>>>>>If no one else is seeing it perhaps its to do with our OCIO setup.
>>>>>>
>>>>>>Andrew
>>>>>>
>>>>>>Date: Fri, 29 Jun 2012 14:01:21 -0700
>>>>>>From: Sean Looper<[email protected]>
>>>>>>Subject: Re: [Nuke-users] 6.3v8 OCIO display lut
>>>>>>To: Nuke user discussion<[email protected]>
>>>>>>Message-ID:
>>>>>>
>>>>>><ca+dgjnax09z0blpa2xogbqr_ofdbkfw0ehwp2gg1h9z6dvp...@mail.gmail.com>
>>>>>>Content-Type: text/plain; charset="windows-1252"
>>>>>>
>>>>>>Hey Andrew,
>>>>>>
>>>>>>Can you clarify a bit? In 6.3v8, the shipped LUTs seem to apply
correctly
>>>>>>to non-rgba channels, but not to the alpha. This is the desired
behavior.
>>>>>>At one point there was a bug in OCIO that caused the LUTs to only apply
to
>>>>>>RGBA, but that fix seems to be picked up in Nuke 6.3v8. Which LUT are
you
>>>>>>selecting in the Viewer LUT pulldown? Are you using a custom OCIO
config or
>>>>>>the one that ships with Nuke?
>>>>>>
>>>>>>Sean
>>>>>>
>>>>>>
>>>>>>
>>>>>>On Fri, Jun 29, 2012 at 12:18 PM,<[email protected]>
wrote:
>>>>>>
>>>>>>
>>>>>> It
appears that the forced OCIO display lut in 6.3v8 is only applying
to
>>>>>>> the RGB channels and not the alpha or other layers.
>>>>>>>
>>>>>>> My "layer" option in the OCIOCDisplay panel is set to all. Though
changing
>>>>>>> this to other options doest not have any affect.
>>>>>>>
>>>>>>> Anyone else experiencing this?
>>>>>>>
>>>>>>> -Andrew
>>>>>>>
>>>>>>> --
>>>>>>> Compositing Supervisor
>>>>>>> ––––––––
>>>>>>>
>>>>>>> MIRADA
>>>>>>> Purveyors of Handmade Storytelling,
>>>>>>> Since 2010
>>>>>>>
>>>>>>> 4235 Redwood Avenue
>>>>>>> Los Angeles, CA 90066
>>>>>>> +1 424 216 7470
>>>>>>> mirada.com
>>>>>>>
>>>>>>> Please consider the environment before printing this email.
>>>>>>>
>>>>>>> This communication is confidential and may contain legally privileged
>>>>>>> information related to Mirada. If you are not the named recipient,
please
>>>>>>> contact us immediately and delete this message and attachments. You
must
>>>>>>> not copy, use or disclose this communication, or any attachments or
>>>>>>> information in it, without our prior consent. All opinions,
conclusions and
>>>>>>> other information expressed in this message not of an official nature
shall
>>>>>>> not be deemed as given or endorsed by Mirada unless otherwise
indicated by
>>>>>>> an authorized representative independent of this message.
>>>>>>>
>>>>>>>
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