Re: Profile of a photo lab
Re: Profile of a photo lab
- Subject: Re: Profile of a photo lab
- From: "john castronovo" <email@hidden>
- Date: Sun, 27 Sep 2009 23:21:25 -0400
I run a color managed photo lab and I can say from hard won experience
that almost everyone in the chain from the manufacturer down has no idea
how to totally stop their machines from adjusting images. Even when you
specify that files be printed with "corrections off" and the operator
thinks that the machine has been put in such a mode, most of the time
you will get unpredictable results if you're trying to work in a color
managed workflow because something is still working on the files behind
the scenes. Totally turning automation off was something that few
equipment engineers provided for and it takes special attention to do it
even when the option is apparently there.
So, the first thing you need to do is to make sure that there are no
adjustments being made to your files, otherwise profiling is a waste of
time. To this end, run a few test files where the same gray background
has different large saturated color squares as well as black and white
on it. No matter what color square you put on the background, the gray
frame background around the square should always be the same. If not,
you can't profile that lab. If yes, proceed to print RGB targets on the
primary (usually glossy) paper just after a machine calibration has been
done since chemistry changes during the day will change the results.
You should always give RGB files to a photo lab, hopefully ones that
were not converted from CMYK, but original RGB files.
About half of our work is printed this way and for the rest, we make
adjustments to images on the fly to make a pleasing result the way most
labs do it. We need to ask what the customer expects in most cases.
john c.
tech photo & imaging
----- Original Message -----
From: "Ray Maxwell"
Hi Jon,
I think you are going to have several problems with profiling a photo
lab. The first is finding out if they use a laser printer that images
on silver halide photo print material or if they use a half-tone
printer
to produce the prints. The next problem is that most photo lab
software
has automatic color correction based on the content and lighting that
you used. The software tries to automatically adjust to produce
pleasing color. The automatic color balance that is done will mean
that
the color adjustment done to a test file may not be the same as a
typical photo that you send to them.
I am told that some labs can turn off this automatic adjustment.
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