Re: Review: added ociobuildicc app


Malcolm Humphreys <malcolmh...@...>
 

Hi Joesph,

When building ICC profiles I've found it very helpful to use the InputTables of the AtoB0 to hold an intermediate conversion, for instance the a 1024 entry 1-d conversion from Cineon to video . The CLUT can then just hold the 3d portion of the conversion I found the match was much improved going that way without having to create a large 3d lut. It's really helps out if you are working with linear space source files in Photoshop.
Effectively this is what is being done with our matte painting allocation, and it does help out a lot.

It does bring up something, I'm looking at replacing the lut builder (non icc luts) I wrote before the switch to OCIO, with OCIO. I was hoping to implement a 1D Sampler (prelut/shaper) and a 3D Sampler for the cube. It would be cool to be able to tag a colorspace as being able to used for the 1D Samplers.

I was thinking about some group of allocation spaces?

.malcolm

-Joseph

-----Original Message-----
From: ocio...@... [mailto:ocio...@...] On Behalf Of Malcolm Humphreys
Sent: Thursday, January 27, 2011 11:00 PM
To: ocio...@...
Subject: Re: [ocio-dev] Review: added ociobuildicc app

Also added Little CMS to LICENSE file

Commit:
https://github.com/malcolmhumphreys/OpenColorIO/commit/8ff296f8ab234ea7b06704036037bf2a132ebd6a

.malcolm

On 28/01/2011, at 5:49 PM, Malcolm Humphreys wrote:

Attaching some slightly larger examples :)


On 28/01/2011, at 5:46 PM, Malcolm Humphreys wrote:

Added ociobuildicc app which will build a soft-proofing icc profile for a given working space.
(added LCMS2 into ext)

Commits:
https://github.com/malcolmhumphreys/OpenColorIO/commit/1b0d39fb10db10
f4edbf1fb0fed124b548b836d9

Attached is an example of two profiles in action.

From the left
* sRGB reference image (ocio cpu)
* matte paint allocation space
* log space image.

The visual difference in the log image is most likely caused by 16bit
quantization errors in the CLUT of the AToB0Tag. These errors are
less with the matte paint allocation as the distance to travel is less.

I did play around with supporting the new MPE D2Bx and B2Dx tags
which should make this problem go away
(http://www.color.org/ICCSpecRevision_02_11_06_Float.pdf) but couldn't get it too work reliably so I pulled it out till I can.

.malcolm



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