Re: OptiCal Spyder USB Problems
Re: OptiCal Spyder USB Problems
- Subject: Re: OptiCal Spyder USB Problems
- From: email@hidden
- Date: Mon, 16 Dec 2002 08:52:19 EST
In a message dated 12/14/02 1:34:08 PM, email@hidden writes:
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1. The manual above says that if you are in a pre-press environment and
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preparing CMYK files for press (which I am) and output or view your prints
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in a 5000K lightbooth (Which I don't have in my office yet, but I use in
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a
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lightbooth at the printer. In my office right now, I only have 5000K
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flourescent light bulbs in the ceiling fixture, which I know isn't ideal,
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but hopefully better than the warm white I used to have.) then you should
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set the OptiCAL gamma at 1.8 and the Calibration Target Settings to
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5000K/D50. Does that sound reasonable? I've read conflicting information
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from various resources about this topic.
This is in there to comfort the old school users... many on this list happily
use monitors at 6500 with lightboxes (or room lights) at 5000. After all, if
I want an image to be as yellow as a MatchPrint, I apply a match print
profile to it, and check the "paper white" box in the Photoshop custom
proofing settings, instead of turning my entire universe yellow with a 5000k
whiteppoint.
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2. In the past, I've calibrated my same MAC monitor with Lacie
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software/hardware (although I know that won't change any physical thing
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in
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my MAC monitor like it does in the Lacie monitors), then have gone into
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the
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RGB sliders in Adobe Gamma and adjusted them separately ("tweaked") to
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make
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the screen view match some color proofs from a particular printer that
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I was
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preparing files for
This violates the profile from the LaCie software; you can't use it and Adobe
Gamma as well, any more than you can use OptiCAL and Adobe Gamma at the same
time...
(I couldn't find in the LACIE software where you could
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adjust the RGB colors SEPARATELY). (I believe I'm using CMYK profiles
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correctly when viewing the files used for these proofs.) Then, I saved
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that
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tweaked monitor profile. Since proofs from different printers look
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different, this seemed a reasonable approach
No, fix the proofing profiles, not the monitor profile...
to monitor calibration before
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I
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color correct files for a particular printer.
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But the things I've read about monitor calibration don't say to do this.
Yes, because they are describing global color management (making your
monitors and printers all accurate) not closed loop color management
(screwing up your monitor to resemble your screwed up proof)...
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However, Don Hutchison's ColorSync article on the Apple Web site says to
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do
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this while looking at a piece of neutral white proofing stock (but proofing
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stock from where? From whatever commercial printer you're going to? From
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whatever injet printer you're going to? Does it matter?). He also says
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don't
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pick a certain temperature like 5000K, that you should end up with the
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appropriate temperature by doing the tweaking.
This is the finest level of detail for the most particular user... not a
place for the beginner to get hung up...
In any case, I can never
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get
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white on my monitor to match any blank white proofing stock I view beside
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the monitor. What are your thoughts on these approaches?
Matching the color and the luminance of a typical paper sample is fine, but
again, I use lots of papers, some more whitened then others, some beige and
some brilliant, and I use the paper profile to emulate this, not the monitor
profile... you want a generally correct setting for the monitor, and one you
can maintain over time.
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3. I noticed that my newly-OptiCAL-calibrated-monitor view of a file, using
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that printer's custom CMYK profile that I ASSIGNED to the file, does not
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look like the same color as that printer's proof of the image, and I know
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that this printer matches their proofs almost exactly on press.
First learn when to assign and when to convert, then work with displaying RGB
files on your monitor, then move to CMYK.
The image
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on
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my monitor looked too green. I thought I would try to tweak the RGB curves
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that are available in OptiCAL to get the screen view to match those proofs,
Only if you are absolutely convinced that for all uses, your monitor profile
is universally off tone, or off density. Otherwise its the printer profile or
proofer profile, that you should be dealing with.
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or to TRY to match the color of some white proofing stock. I thought maybe
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if I took out a little green by altering the green curve, or tried altering
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one of the other curves so that the image didn't look too green, that might
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be the right thing to do. But, the points on the curve are not smooth
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points, and I find the curves box confusing. For one thing, I didn't have
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the options "calibrated" and "uncalibrated" like the manual says. And,
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I
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altered the curves while looking at the image, but when I closed the box
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and
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went into Photoshop, the color of the image looked very different than
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it
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did while I was altering the curves.
You are using this tool incorrectly. Photoshop uses the profile the curves
define, so clicking back on Photoshop will change the view. You actually need
to build a new profile from these target changes.
Should I forget about this tweaking
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stuff? Please comment.
For the moment, yes, definately forget about it, there are lots of other
items that should be dealt with first.
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4. I've never read a good explanation about why you would use 1.8 gamma
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as
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opposed to 2.2 gamma.
Because non-color-managed applications on the Mac will assume 1.8. If you
don't care about that, then feel free to use 2.2; many do.
Bill Willmore, for example, in one color management
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article, suggested using 2.2 for MACs, then in his new book, he suggested
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using 1.8 for MACs, but didn't go into great detail about why in either.
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I've noticed that the gamma, while I've read that it refers to the
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brightness of the midtones, affect the shadow areas in addition to the
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midtones.
If effects everything between black and white, effecting the middle the most,
and the ends the least. Its like grabbing a clothes line and pulling to the
side; the ends are secured and don't move, but everything else does.
If my monitor is darker than it should be, I'll tend to lighten
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the shadow areas too much when I'm correcting. If it's lighter than it
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should be, I'll tend to darken the shadows too much when correcting. So
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how
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do I know I've calibrated with the appropriate gamma?
Photoshop will correct for your chosen gamma, so a 1.8 and a 2.2 calibrated
monitor will both display the image identically, as far as gamma is concerned.
C. David Tobie
Design Cooperative
email@hidden
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