Re: CMYK/RGB printing confusion - please help!
Re: CMYK/RGB printing confusion - please help!
- Subject: Re: CMYK/RGB printing confusion - please help!
- From: Uli Zappe <email@hidden>
- Date: Thu, 3 Mar 2005 00:35:46 +0100
Am 02.03.2005 um 20:28 schrieb Chris Murphy:
On Mar 2, 2005, at 11:37 AM, Uli Zappe wrote:
\/ Printers
\/ ColorLaserJet 5500 *
CMYK Matching Profile *
Gray Matching Profile
sRGB Matching Profile
Do they let you associate a custom profile for the "sRGB Matching
Profile"?
Yes.
This isn't making much sense. Is the manufacturer specified profile in
this location sRGB?
Seems to be so, though it's a bit ambiguous. The file name is
"sRGB_A.icc" which suggests sRGB, but the profile name is "hp color
LaserJet RGB v402".
That would make sense. And then you could replace it with something
better if you made a custom profile. But calling the setting "sRGB
Matching Profile" doesn't make sense to me unless a.) the manufacturer
specified profile is sRGB, and b.) you can't change it to anything
else.
a) yes, b) no, it's maybe a misnomer.
The Epson drivers are luny when it comes to supporting ColorSync
correctly.
At least the colors are OK ... (in my case)
You would think ColorSync would normalize everything to Gray and CMYK
for a CMYK device. Any RGB content would be converted to CMYK as well.
I'm a little mystified as to what exactly the OS is going to do if an
application submits RGB data for a printer that has a default color
mode of CMYK.
Maybe the idea is if you edit the PPD to change the default color
space to RGB? Then the OS would normalize everything to sRGB and the
printer would have to do an internal conversion to print sRGB color
correctly?
I thought of that, too. I mean, first I was sure that ColorSync Utility
provides some way in its GUI to change the default. This is obviously
not the case. Then HP told me I must choose the color space in my app.
This seems to be nonsense, too. So, yes, what remains is this (I
haven't tried it yet, though). You could even create an additional
profile, add a second printer entry in the Printer Setup Utility for
the same CLJ 5500, but with the modified PPD, and in this way switch
between the two color modes in the GUI.
After this is done, it would even work nicely for a plain user. But
this just *can't* be the way it's meant to be ...
Documentation is underrated.
Yes! <Sigh> As is support that has a clue ...
Compared to what I see on the screen in my original document, for me,
"In Printer" is, well, acceptable, while "Standard" is far too dark.
It is consistent with the Soft-Proof in Preview, though, that is also
far too dark! (E.g. a blue of HSV 216-73-79 becomes 214-69-65 in the
Soft-Proof mode of Preview, and the print looks accordingly.)
Sounds like a jacked up profile. The B2A portion is converting too
heavily (incorrectly) and the A2B portion is predicting it!
But as I said, this tendency is already obvious when converting to e.g.
Apple's Generic CMYK profile. This is something I don't understand.
E.g. Make a screenshot of a typical blue Aqua button, save it as TIFF,
open the TIFF in ColorSync Utility and apply a Quartz filter that
converts the (RGB) TIFF to the Apple supplied Generic CMYK. If you
check the "Preview" checkbox, the shining Aqua blue becomes dull.
Always? I mean, even when I have an image with an embedded CMYK
profile? This gets converted to Monitor RGB and then back to CMYK in
case of a CMYK printer?
Yes. Preview is not a good color management citizen.
Ooops! :-( Is this also true for Cocoa apps in general, e.g. if I add
a CMYK image to TextEdit and then print from TextEdit (no Preview
involved)?
On a side note, wouldn't that mean that you should always use Monitor
RGB as your working space? I mean, it's one conversion less, and
that's good, isn't it?
"working space" is an Adobe term for settings found in Adobe
applications. You can't set a working space for non-Adobe
applications.
Apple, in its "Color Management with Mac OS X Panther" documents (as
well as other ColorSync related documents), also uses the term, without
any reference to Adobe apps. On page 13, it recommends using
AppleScript to convert images to a working space.
HP support is probably not going to be able to tell you squat. You
need to find an engineer who worked on the PPD for Mac OS X, or the
guy who built the ICC profile.
Over that long last year, I think I have come as close to the HP
engineers as I will ever be able to come ... :-(
How far away are you from Barcelona?
Looking at my outdoor thermometer, faaar away. ;-)
I think they have an entire cabal of engineers there. You could just
pay them a visit. Ha!
Ha! 8-}
Email me the PPD for the printer. I'll set up a dummy printer, print
PostScript to a file and see what I get from a few apps.
I'll send it to you in a private email.
If possible, I'd want to avoid buying an Adobe app for just *that*.
=8-} Any other way? What about printing directly from the command
line (lpr)?
Never tried it. Surprisingly enough Mail.app might be able to do this
:)
Then TextEdit should, too, shouldn't it?
If you take the CMYK target, and use the Embed Specific Profile
AppleScript to embed your canned CMYK profile into the image,
Which "canned profile" do you refer to?
And BTW, this illustrates the rather poor state of affairs of color
management on OS X. We are so needy for Adobe applications, and
there's a lack of an explicit OFF switch for color management that we
can't even easily print profile targets to make custom profiles for
our devices without having a square dance under a full moon with a
dog, a pig, and a pony. The situation is pretty ridiculous...
100% agreed!
What I find additionally confusing, though, is that even converting
an RGB image into the Generic CMYK Profile (in the ColorSync Utility)
makes the image noticeably darker. Shouldn't at least this generic
conversion from RGB to CMYK leave the image as identical as possible?
I thought that's what color management is all about?
Yes.
But it doesn't seem to work this way ...
Tell you what you should do. Try changing the CMYK profile in the
ColorSync Utility for your printer to some other CMYK profiles and see
what happens when you print. Is there a difference?
I have two HP provided CMYK profiles:
CMYK_A.icc (the factory setting for all CLJs, per the new PPD) and
HP Color LaserJet 5500 (an older profile especially for the CLJ
5500).
Apart from these, the only CMYK profile on my system that I could try
was Apple's Generic CMYK Profile.
I tried to print with all 3 of these, and I also tried "In Printer"
mode, but my test image obviously wasn't optimally suited for the job,
because I could hardly tell any difference between the 3 CMYK versions,
while they all 3 clearly differed from the screen. But the "In Printer"
image wasn't as close to the screen as I remembered, either.
So I decided to do a more objective test. I created a test TIFF with 3
color squares, with the following colors (in HSV):
Red Green Blue
000-70-70 120-70-70 240-70-70
The TIFF is tagged with my display profile (an Apple 22" Cinema Display
profile).
Then I printed in all modes, to Preview as well as on paper. Here are
the Preview Soft-Proof results for the different modes (in "In Printer"
mode, Preview can't offer a soft proof, of course, so it displays
exactly what it would display with Soft-Proof switched off in the other
modes):
"In Printer": 000-69-69 123-74-72 253-80-69
Generic CMYK: 000-65-67 119-59-67 233-62-52
CMYK_A.icc: 356-72-65 132-78-60 235-67-53
CLJ 5500: 000-66-68 125-69-69 248-67-58
Subjectively, the actual print results looked like the following:
"In Printer": too bright too dark ~ too dark
Generic CMYK: too bright too yellow too dark
CMYK_A.icc: OK ~ too dark too dark
CLJ 5500: OK OK too dark
So, apart from the fact that *every* mode produces a blue that's more
or less too dark (and much too dark with every CMYK profile), the CLJ
5500 profile isn't as bad as I thought; maybe I can indeed get decent
color with a CMYK custom profile. Though I ask myself why each and
every CMYK profile (Apple's own Generic CMYK included) is so far off
with blue?!?
What I find totally strange, though, is that in "In Printer" mode - or
with Soft-Proof switched off in Preview (which is identical as far as
Preview is concerned) - there are such big differences, or any
differences at all, for that matter. If I open a TIFF in Preview, and
print from there into Preview again, why is there a difference?
Shouldn't this be exactly the same? It's the same image, displayed in
the same app, with color management explicitly switched off - why is
there a difference? This is a mess. :-(
Faster and easier than what? Jaguar perhaps? That was Mac OS X public
beta #2.
Very true ...
That book, commissioned by Apple, laments the bypassing of ColorSync
by Adobe applications and yet that's the only way to get the best
possible results due to lack of black point compensation and rendering
intent selection in Apple's implementation.
Hm, you can specify rendering intents for Quartz filters in ColorSync
Utility.
Plus, the lack of an aforementioned Off switch so we can easily print
targets without an Adobe application.
EPSON were clever enough to include a "No color management" option in
their Print Panel options.
A big part of the problem is the lack of effective communication and
documentation between developers and Apple. I'd bet that the reason so
many developers aren't doing the right thing with color management in
their applications is because of the lack of adequate documentation
explaining how to do it correctly.
This includes HP's PPD programmers ...
So far the situation from the end user perspective hasn't improved
much with successive releases of the OS.
Not really. :-(
Bye
Uli
________________________________________________________
Uli Zappe, Solmsstraße 5, D-65189 Wiesbaden, Germany
http://www.ritual.org
Fon: +49-700-ULIZAPPE
Fax: +49-700-ZAPPEFAX
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