Re: ISO 12647-7 "tolerances"
Re: ISO 12647-7 "tolerances"
- Subject: Re: ISO 12647-7 "tolerances"
- From: MSP Graphics <email@hidden>
- Date: Thu, 24 Apr 2008 22:28:12 -0700
The later variations on DeltaE, most recently DeltaE 2000, are better
at corresponding to human perception (and some day the ISO specs will
catch up), but it's still true that a given DeltaE number has vastly
different significance for different colors. We can perceive tiny hue
differences in grays, only pretty big hue differences in dark colors,
strong yellows, and so on. Some people become alarmed at seeing a
peak of 5 or 6, but it may be in a color where it can barely be seen.
Profiling software can also shift the biggest errors into less
critical colors--but perhaps someone more familiar with that subject
can address it further.
Mike Strickler
MSP Graphic Services
423 Aaron St. Suite E
Cotati, CA 94931
ph. 707.664.1628
fx. 707.939.4542
www.mspgraphics.com
Message: 6
Date: Thu, 24 Apr 2008 16:01:31 -0400
From: Kevin Muldoon <email@hidden>
Subject: Re: ISO 12647-7 "tolerances"
To: email@hidden
Message-ID: <email@hidden>
Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed
Thanks for forwarding the PDFs Mark. Fascinating stuff. I see your
point on high chroma colors vs. low chroma, though I never suspected
the 'high-chroma = more room for L*a*b deviation' nature of high
chroma colors.
Color guys understand the human eye is very sensitive to neutrals. I
think we have all compared and measured greyscale steps from
different printers that register well below a deltaE 2 tolerance
between then, but (at least to my eye) are obviously not the same
grayscale at all. I see the same phenomena with paper white of
different medias as well as very light colors. In other words, L*a*b
DeltaE says I can't see a difference, but I do. I understand there is
a calculation to modify the DeltaE for lighter colors, but haven't
heard of addressing sensitivity to neutrals and off neutrals.
I'm going to have some fun tinkering with this! Think I'll start with
some grayscale wedges.
--
Kevin Muldoon, Owner
TrueBlueDot - Fine Art Printing
New Haven, CT 06511
email@hidden
www.truebluedot.com
"Our pigment meets your imagination"
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