Re: Colormatch vs Adobe 98
Re: Colormatch vs Adobe 98
- Subject: Re: Colormatch vs Adobe 98
- From: email@hidden (Bruce Fraser)
- Date: Fri, 1 Feb 2002 09:44:20 -0800
At 11:22 PM -0800 1/31/02, Chris Cox wrote:
At 12:19 PM -0800 1/31/02, email@hidden wrote:
CIE colorimetry is based entirely on comparison of reflective
samples. It was never designed to handle emissive samples.
Sorry Bruce.
Most (if not all) of the experiments leading to the CIE standards
were light (emissive) based.
Chris, Robin, Don,
I should have made myself clearer. The experiments that led to the
standard observer and XYZ were indeed emissive-based, but XYZ has no
white point dependency. Most of the work on LAB and LUV was based on
reflective samples. But mainly, none of it was based on comparing
reflective and emissive samples.
Your eye cannot tell the difference between an emissive image and a
reflective image -- when seen under the same viewing conditions
(absolute brightness, no flicker, same surround, etc.). (this has
been done at RIT, many times)
The problem isn't viewing either reflective or emissive in isolation
(unless you do the simple trick of moving the light box so that it
isn't in the same field of view as the monitor) -- it's when you try
to view them both at once.
The common "monitor D65 is the same as viewing booth D50" comes
about mostly from the difference in absolute brightness.
My experience is that even when you take care of matching absolute
brightness, monitor images at D50 have red highlights compared to
transparencies in a D50 light box. It's less of a problem matching
prints and proofs, but I still see discrepancies that aren't related
to absolute brightness.
There are also spectral differences that exaggerate the apparent
color difference. I've yet to see a fluorescent bulb that would give
a decent D50 spectrum.
Ditto.
For those that want all the gory details, I recommend reading Mark
Fairchild's "Color Appearance Models".
Me too.
Bruce
--
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