Re: Trouble profiling LaCie monitor
Re: Trouble profiling LaCie monitor
- Subject: Re: Trouble profiling LaCie monitor
- From: David Foster <email@hidden>
- Date: Wed, 26 Jun 2002 17:34:39 -0400
I have been travelling and was not able to respond to everyone who wrote
with suggestions of help, for which I am very grateful.
We've gotten responses from consultants as well as from individual users,
and come up with the following:
As suggested, we replaced Colorblind's ProveIt with the latest version, and
replaced the LaCie 19 with the LaCie 22 that has the hardware calibration
cable. After re-calibrating and re-profiling with a new Chroma4 puck, the
differential non-linearity (adjacent neutral patches appearing different
colors) is still as prevalent as before, although somewhat worse with the
ProveIt than with the LaCie software. One thing we can report with complete
confidence is that the 22 inch monitor is bigger than the 19 inch.
Tom Lianza wrote:
" A very common problem that causes this artifact is
differential non-linearity or missing codes in the graphic cards output
Digital to analog converter. It is hard to imagine a situation where an
analog monitor would behave in such a discrete manner, and I can understand
the skeptisim of the display manufacturers especially given their knowledge
of the graphics card situation."
This seems to make sense, however, why would the same CPU/graphics
card/monitor combination display a smooth gray ramp with no differential
non-linearity with a canned profile? (If we change the profile of the Lacie
to one of the Mac's canned profiles, the gray ramp is smooth.) Wouldn't it
be the profile itself, since that's the only thing different in the
comparison? The gray from the canned profile isn't quite right, but there
is no difference between the neighboring patches. If it is that the video
card can't perform with a custom made profile, how can one judge the quality
of video cards in general? Does more money = better quality?
C. David Tobie wrote:
"All 256 levels of RGB gray (R=G=B) view neutrally on screen; generally
with no assistance, but occasionally a monitor will require a bit of special
tweeking to reach that point."
and Keith Brodie at email@hidden wrote:
"I look for specific areas that appear the most 'off' and correct
for them first using the curves in the calibration software. It's
just like color correcting using curves in photoshop, except it will rely on
the setup of the curves window in the profiling app you use."
If there is a christmas tree of differences between levels of gray, both in
a simple ramp (16 levels from 0 to 255) and a complete ramp (255 levels),
how does changing the curves work? It's not that the lower end of the curve
looks too warm, it's that the 16,16,16 looks warm, the 17,17,17 looks blue,
and the 18,18,18 looks yellow. When I change the curve in the window, it
shifts all the grays in that area globally, and the difference between the
neighboring patches remains. I'm trying to figure out if we are reaching
the end of the useful abilities of the color management tools available.
I can't stress enough how much help every one has been - hopefully we will
be able to answer someone's questions.
Thanks,
David
--
David Foster
David Foster Photography
840 Summer Street
Boston, MA 02127 USA
Tel: 617-464-2295
Fax: 617-464-2495
http://www.davidfosterphotography.com
email@hidden
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