Re: Delta E calculator
Re: Delta E calculator
- Subject: Re: Delta E calculator
- From: Steve Upton <email@hidden>
- Date: Tue, 1 Jul 2003 16:28:22 -0700
At 11:14 AM +0100 7/1/03, Simon Winnall wrote:
>
I'm doing some research into litho printing, trying to evaluate acceptable
>
tolerances for process colour printing. In your opinion, what would
>
acceptable tolerances (Delta E) be for the categories below:
>
>
1. Fine art reproduction
>
2. Brochure printing (high quality)
>
>
I would appreciate your opinions.
I wish I could give you an easy answer but instead I have a warning.
Beware "simple" Lab calculations. Unless you use delta-E 94 or CMC you will find that delta-E number values do not correspond with actual perceived color differences.
it's true that Lab was defined so that the simple 3D distance between any two points is a good method of comparison but in reality it turns out that the current version of Lab that we are all using is non-isotropic - that is it is warped, and warped more in some areas than in others. Lab, when compared with perceptually accurate systems like Munsell can introduce errors of 20% or more in certain areas.
so... beware.. if your tools do not use newer flavors of delta-E, they are prone to error.
Regards,
Steve
________________________________________________________________________
o Steve Upton CHROMiX www.chromix.com
o (hueman) 866.CHROMiX
o email@hidden 206.985.6837
o ColorGear ColorThink ColorValet ColorSmarts ProfileCentral
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