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: Wed, 2 Mar 2005 19:37:11 +0100
Am 02.03.2005 um 18:02 schrieb Chris Murphy:
I wouldn't expect an output device could be registered as being either
CMYK or RGB. It's one or the other.
I thought so, too.
However, if you install the current PPD for a CLJ 5500, this is what
you see in ColorSync Utility > Devices:
Registered ColorSync devices:
Device Default
> Scanners
> Cameras
> Displays
\/ Printers
\/ ColorLaserJet 5500 *
CMYK Matching Profile *
Gray Matching Profile
sRGB Matching Profile
\/ Stylus_Photo_R200
SPR200 R210 Matte Paper-HW
SPR200 R210 Photo Paper
SPR200 R210 Standard *
SPR200 R210 Premium Glossy
SPR200 R210 Photo Quality IJP
SPR200 R210 ColorLife
> Proofers
["*" is a blue dot in the Aqua GUI]
The EPSON Stylus Photo R200 that I show as a comparison has several
entries for different profiles, too. However, these are all RGB, and I
suppose they get chosen automatically dependant on what kind of paper I
specify in the Print panel.
But the HP CLJ 5500 has three entries for three different color spaces.
In each entry, you can specify a custom ICC profile with the respective
color space.
This PPD was the result of my year-long quest of a working PPD for the
CLJ 5500. The former PPD had only one entry. This was obviously an RGB
entry, because only RGB profiles could be chosen as custom printer
profiles; however, these profiles had no influence whatsoever on the
printing result.
That the CMYK entry is marked as default in ColorSync Utility is
obviously the result of an entry in the PPD:
*% =================================
*% Basic Device Capabilities
*% =================================
*ColorDevice: True
*DefaultColorSpace: CMYK
But OTOH the PPD specifies factory profiles for all color spaces:
*% =================================
*% Product/PPD Version Information
*% =================================
*% PPD File Version Information
*cupsICCProfile RGB../sRGB Matching Profile:
"/Library/Printers/hp/Profiles/sRGB_A.icc"
*cupsICCProfile CMYK../CMYK Matching Profile:
"/Library/Printers/hp/Profiles/CMYK_A.icc"
*cupsICCProfile Gray../Gray Matching Profile:
"/Library/Printers/hp/Profiles/Gray_A.icc"
Now, of course the question is, why would the PPD specify RGB and Gray
profiles if these cannot be used in any way?
If they don't register the device as allowing RGB, then indeed it
makes no sense for the manufacturer to provide an RGB profile that you
can't use
What exactly means "register" in this context? That CMYK is specified
as default? I mean, the PPD seems to "register" CMYK, RGB and Gray with
the ColorSync Utility ...
HP support says that I have to switch the color space I want to print
with in the app I want to print from.
Absurd. HP support sounds clueless.
<Sigh> This goes on for over a year now ...
If they a.) register the device correctly, specify driver defaults
that were used to build the profile they made for the printer (RGB or
CMYK), and provide a well built profile that describes the printer's
behavior with those settings - the conversions necessary will all
occur behind the scenes whether you use Standard or In-Printer
ColorSync settings in the print dialog (with Standard generally being
more reliable.)
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.)
Preview converts everything it opens to Monitor RGB (whatever profile
you have set for your primary display), and then displays it. That
same converted data is what gets printed.
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?
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?
Or do I get this wrong and the PDFs Mac OS X creates for printing do
not contain an ICC profile? [...]
They do contain an ICC profile.
My confusion is that Preview does show an ICC profile and a color space
for images (TIFF etc.) I open in it directly, but *not* for PDFs. Is
this simply a bug in Preview's info panel?
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 ... :-(
You may invariably need a custom profile anyway.
Well, that's what I intend to do. It's just that before I start dealing
with/investing in that, I wanted at least to make sure that I am ready
for that in that I have understood the necessary prerequisites. So far
I haven't. Up to now, I didn't even know if I need to build a custom
CMYK profile, a custom RGB profile, or both ... :-/
To print the target correctly means NOT using Preview. You'll need to
print using an application that does not convert images when opening
them, like Preview does. If you're using any Adobe application, you
can ensure that you're getting a non-color managed target from which
to have a profile built.
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)?
Then simply use that profile in the ColorSync Utility. While this has
fairly poor reliability with non-PostScript inkjet printers using
manufacturer's drivers, it does seem to work reliably with the limited
testing I've done with PostScript inkjet and laser printers.
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?
(But the user interface is far far less than intuitive.)
Apple writes in the introduction of "Color Management with Mac OS X
Panther":
"With Panther, it is faster, easier [...] than ever to achieve
consistent color."
And I thought I was an experienced computer user ... :-/
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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