[argyllcms] Re: colour management and... photo lab
- From: <m.kaluza@xxxxxxxxx>
- To: <argyllcms@xxxxxxxxxxxxx>
- Date: Thu, 23 Jun 2011 12:44:18 +0200
Calibration, quality of media and so on is another story.
From color management perespective the major problem is that the minilab
software has automatic, simple sRGB>internal profile LUT conversion, and it's
difficult to turn it off. We can profile the output to softproof the machine's
behavior. We can also use such external profile to convert RGB numbers and
"tweak" the color rendering, but so or so the paper gamut is cutted with sRGB
gamut:
http://members.chello.pl/m.kaluza/qss1.jpg
...and the internal convertion applied by minilab software spoils the tonality
of 8 bit jpeg image.
There's a workaround - when we print from Noritsu printer driver the internal
CMS is inactive, so all we need is to print the target and profile the output
in so called Noritsu NetOrder mode - as a result there's much larger gamut
available (in this case - Kodak Endura Supra Proffessional VC):
http://members.chello.pl/m.kaluza/qss2.jpg
Another advantege is better tonality - we only make one convertion, and we can
convert using 16bit depth to the destination profile, so b&W photos have better
smoother transitions without color casts.
An example - these jpegs are screenshots, so they're in a color space of my NEC
3090WQXi wide gamut display:
an image converted to the "external" profile that's characterisig Noritsu in
QSS mode, where the paper gamut is limited by sRGB gamut:
http://members.chello.pl/m.kaluza/qss4.jpg
same image converted to profile of Noritsu in NetOrder mode:
http://members.chello.pl/m.kaluza/qss3.jpg
The only problem is that printing from Noritsu printer driver is problematic,
and you need some additional software to manage printing of large amount of
images, and the operator must understand the basics of color management (at
least) - so it's not that easy to implement such worflow in real world
practice.
Marcin Kałuża
----- Original Message -----
From: Marek Matulka
To: argyllcms@xxxxxxxxxxxxx
Sent: Thursday, June 23, 2011 12:58 AM
Subject: [argyllcms] Re: colour management and... photo lab
Hi Marcin,
That's what I actually expected. Results from photobox and digilabpro are
like that - sRGB/noICM images are identical. Funnily, Jessops printed images in
the way, they differ, even between sRGB/noICM images... weird.
My test images are here: http://pub.matulka.net/lab-test-prints/
Funnily enough, on british airways plane, the AdobeRBG prints have the most
accurate colour of the sky... though it's bit to dark and undersaturated.
I guess, the problem lies in the fact, labs don't calibrate their machines
and that's it. so it prints inaccurate colours even though they claim they work
in sRGB colour space. This is the same as with monitors - over time they
decrease in quality, brightness etc... so they should be recalibrated regularly.
Many thanks,
Marek
On 21 June 2011 15:07, <m.kaluza@xxxxxxxxx> wrote:
Hi list!
Marek - according to my experience with minilab printers, most machines
doesn't color manage the images at all. In case of Noritsu QSS/Fuji
Frontier/Agfa dLab the software applies simple, internal LUT sRGB>minilab
conversion, so it doesn't even bother what's the color space of the image.
Therefor you shouldn see any difference between untagged and tagged sRGB image,
because only RGB numbers really matter. Only Adobe RGB rendered file (with
different RGB numbers) should look different - in fact it should be the most
inaccurate one, with slightly desaturated colors.
Marcin Kałuża
----- Original Message -----
From: Marek Matulka
To: argyllcms@xxxxxxxxxxxxx
Sent: Monday, June 20, 2011 12:09 AM
Subject: [argyllcms] colour management and... photo lab
Hello everybody,
I've been subscribed to this list for quite a while.
Anyway, yesterday I've done a “test” - developed (raw -> jpg) 5 photos,
each one in three versions: with Adobe RGB profile, with sRGB profile and
without profile. So resulted in 15 photos, which I had printed at Jessops in
Kingston.
My expectations were as follows: photos with Adobe profile should be more
or less identical to those with sRGB embedded (as I see it that way on my
screen), photos without profile should be either printed as they were, or
should have sRGB profile assumed.
To my surprise, all photos were printed differently!
Adobe RGB prints shown right colours, but all prints were darkened.
sRGB prints shown colours as if no profile was used, photos without
profile were similarly printed to those with sRGB profile, yet still were bit
different.
When processing my order at Jessops (yes, you have to do via their kiosk,
they are unable to print your prints from the CD apparently!) I've selected an
option not to correct colours etc.
So, I am lost. I've sent same test photos to photobox and a digilab pro
in London, I am still worried, that I'll get similar results...
any ideas how to get best prints from the lab? having calibrated
environment at home?
Many thanks,
Marek
--
http://marek.matulka.net/
--
http://marek.matulka.net/
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