Re: Colormatch vs Adobe 98
Re: Colormatch vs Adobe 98
- Subject: Re: Colormatch vs Adobe 98
- From: Don Hutcheson <email@hidden>
- Date: Thu, 31 Jan 2002 19:38:24 -0500
Bruce,
You are absolutely right. I was relying on a spreadsheet I whipped up six
months ago with an error in it. Come to think of it, back then I was
surprised to find such high gammas matching L* so well because my prior
tests had shown 2.2 to be pretty optimum.
What I like about gamma 2.2 is it actually assigns more precision in dark
tones than L*.
Thanks for pointing out such an obvious error.
Don
*************************************
Don Hutcheson
Hutcheson Consulting
(Color Management Solutions)
Phone: (908) 689 7403
Mobile: (908) 500 0341
email@hidden
*************************************
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From: "Bruce J. Lindbloom" <email@hidden>
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Date: Thu, 31 Jan 2002 13:11:19 -0600
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To: ColorSync User List <email@hidden>
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Cc: <email@hidden>
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Subject: Re: Colormatch vs Adobe 98
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>
Don Hutcheson wrote:
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> WORKING SPACE:
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> You absolutely SHOULD use a gamma 2.2 working space rather than 1.8, as 2.2
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> distributes tonal values more evenly throughout the visible lightness range
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> and preserves more shadow detail for later exhumation. In fact higher gammas
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> like 2.4, 2.6 or even 2.8 are theoretically closer to the ideal L* curve and
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> distribute the 256 levels even better from whites to blacks, but may
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> increase the risk of banding in lighter tones.
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>
I would be interested in learning how you determined that such high gamma
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values (2.4 to 2.8) are "theoretically closer to the ideal L* curve." I have
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also studied this problem, but have come to a different conclusion. I found
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the best fit gamma value to be smaller than those you give, and in fact, it
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depends on how you define "best":
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If "best" means minimizing the largest difference, then gamma = 2.1723
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If "best" means minimizing the RMS difference, then gamma = 2.3243
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So I think 2.2 is pretty close to ideal.
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--
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Bruce J. Lindbloom
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www.brucelindbloom.com