Re: Comparing output profiles
Re: Comparing output profiles
- Subject: Re: Comparing output profiles
- From: Derek Cooper <email@hidden>
- Date: Sat, 19 Jul 2003 19:33:45 -0400
Bruce,
Thank you kindly - when you mentioned that you did articulate that in
your book, I started hunting and found it. Nicely done - I figured you
had it documented somewhere.
I'm giving the technique a whirl now to see how it goes - greatly
appreciate your assistance, yet again.
Cheers,
Derek
On Saturday, July 19, 2003, at 07:37 PM, bruce fraser wrote:
At 7:10 PM -0400 7/19/03, Derek Cooper wrote:
Bruce,
In RWCM we have instructions for doing the same kind of comparisons
for output profiles, but I suspect that that's not what you're
looking for.
Page reference? I flipped through it but couldn't find any reference
to that process. I think there's a leap made assuming that the
reference file is already in LAB space.
pp247-250.
No, the reference file is always in the color mode for which you're
building the profile -- RGB or CMYK.
You have one set of LAB values from the measurements. These tell you
what actual color the device produces when fed the numbers in the
target (or target reference file).
You can produce a second set of LAB values by assigning the profile to
the target and converting it to LAB. This gives you the LAB values the
profile predicts. Comparing those to the measurements shows you the
accuracy of the device-to-PCS tables.
You can then take these LAB values, print them through the profile,
and measure the results to produce a third set of Lab values.
Comparing those with the predicted LAB values shows you what's going
on in the PCS-to-device tables.
Finally, you can compare the original measurements with the Lab values
that result from the predicted LABs printed through the profile.
The best tool I know for doing what you want is Steve Upton's
ColorThink. It lets you compare both the gamut of source and
destination profiles, and, more usefully, the gamut used by a source
image with the destination profile, as 3D graphs. (It does much
more, and I find it indispensible.)
Ah, more toys! I'll check it out and see where it takes me. I've been
running in to some "issues" profiling a 2000P for a client. I know
those printers have issues, but they do have the ability to perform
quite nicely.
The biggest issue I find with the 2000P is that the yellow ink has a
green response that isn't triggered at all by tungsten, but gets
progressively stronger at illuminants above 5000K. It's more sensitive
to variations in the illumination than any other print process I've
encountered.
--
email@hidden
_______________________________________________
colorsync-users mailing list | email@hidden
Help/Unsubscribe/Archives:
http://www.lists.apple.com/mailman/listinfo/colorsync-users
Do not post admin requests to the list. They will be ignored.