Re: metamerism & proofing setup
Re: metamerism & proofing setup
- Subject: Re: metamerism & proofing setup
- From: Don Hutcheson <email@hidden>
- Date: Thu, 12 Jun 2003 16:23:40 -0400
Steve,
If you can measure or predict the spectrum of the viewing light, then using
that spectrum to compute 'custom-source' CIELAB or CIEXYZ values for both
devices should virtually eliminate metamerism failure in proofing. It should
also reduce (if not eliminate) metamerism errors in the camera.
Here's how it works (in theory);
1. Take spectral readings of both the printer target and proofer target and
convert the spectral measurements into Lab(customsource) instead of the
normal Lab(D50).
I do this the hard way in Excel but the latest ProfileMaker (4.1.5) allows
you to import any source spectrum and make profiles for that custom source.
But if you can find out how to do it without calling tech support, good
luck!
2. Profile your camera and shoot the original under identical or similar
lighting (yeah, I know tungsten's hot, but it's cooler than metamerism
failure!)
3. Create a reference file for your camera profiling target in the same
spectrum as your camera lights, i.e. Lab(camerasource).
4. Fly me to Hawaii if it works.
NOTE:
A standard ICC CMM always assumes a D50 PCS, so it's important that the
profiles claim a standard D50 PCS white point, even though you and I know
the readings were in a different source. This is assured if you do the
computations in Excel and simply import the modified Lab values into the
profiling package. I don't know what GretagMacbeth are doing in the latest
software.
If the profiles claim anything other than a D50 PCS white point, the CMM
might try to do a redundant, and possibly damaging, transform to and from
D50 when building a link. You might also get weird results in absolute
intent if one of the profiles has a standard D50 PCS white and another
didn't.
Contact me off-line if you need more help.
Don
*************************************
Don Hutcheson
Hutcheson Consulting
(Color Management Solutions)
Phone: (908) 689 7403
Mobile: (908) 500 0341
email@hidden
*************************************
>
From: email@hidden
>
Reply-To: email@hidden
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Date: Wed, 11 Jun 2003 22:00:35 -0700
>
To: email@hidden
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Subject: colorsync-users digest, Vol 3 #848 - 15 msgs
>
>
Message: 12
>
From: "Steven Kornreich" <email@hidden>
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To: <email@hidden>
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Subject: matamerism and proofing setup
>
Date: Wed, 11 Jun 2003 14:54:38 -1000
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>
Wanted everyones opinion on my situation.
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Since all I do is fine art repro and depend heavily on input and output
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profiles, All my ouput is viewed in a gallery setup. Everything being lit
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with halogen par lights. I have made a viewing area in my facility with the
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same lights my work will be displayed under. In regards to building input
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and output profiles everything is all 5000K but none of my work is viewed in
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these conditions. Where would be the best place to start in regards to
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profile useage and building? I wish I lived in a perfect viewing world but I
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don't.
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What I am first thinking is make sure my gray is gray when viewed under the
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halogen lights. So I have to tinker with my base line linearization in
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BestColor to get a good gray before printing my swatches and building my
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profiles. I am not sure what direction to go in.
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Thanks
>
>
_________________________________
>
Kornreich Communications Inc.
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Steven Kornreich
>
email@hidden
>
http://www.beachlook.com
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