[argyllcms] Re: Profiling a Minilab
- From: Philip Pemberton <philpem@xxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Sat, 03 Jul 2010 16:46:12 +0100
On 03/07/10 16:08, Pascal de Bruijn wrote:
Now, I should have done my homework better before sending these images
(I can't cancel them anymore), but it seems Minilabs are actually
real RGB devices? Can anybody confirm this? Should I have used Video
RGB?
Depends on the minilab.
Dry-labs like the new HP boxen are basically inkjet printers: CMYK
devices which print onto rolls of photo paper. Dye-sublimation type
dry-labs use wax instead, but they're still CMYK. The jury's still out
as to whether they're any good for pro use, but AIUI most pro-photogs
won't touch them with a bargepole.
Wet-labs like the Fuji Frontier series are based on an RGB laser
assembly and print onto normal colour photographic paper. The RGB
produces a C/M/Y pattern on the paper (it's negative acting), which is
developed using RA-type (CP48 in the case of Fujifilm) process
chemistry. Much messier, but better quality.
Most of the Frontiers have built-in self testing and colour correction:
a profile built for a specific Frontier will generally remain valid
until major work is done on the printing engine: a major change in
chemistry, replacement laser assembly or something similarly in-depth.
Most lab techs will avoid a chemistry replacement because:
A) it's expensive
B) it kills the machine for about a day
C) it takes a few hundred prints for the replenishment system to
bring the chemistry under control
D) did I mention it takes AGES to do and has to be done to incredibly
tight tolerances?
Noritsu wet-labs are basically identical to the Frontiers in terms of
technology. Newer Fuji minilabs are actually built by Noritsu, but run
Fujifilm's software. Frankly I'd take the Noritsu software, though I
doubt it's much better than Fuji's crashy, buggy blob of goo.
There are also the KIS/Photo-Me and Kodak wet-labs. These use an LCD
display panel to expose the paper (!) then develop like the Frontiers. UGH!
And no, the Lab didn't accept TIFFs (ImageMagick JPEG Q97 disables
subsampling). They did however offer a "no auto correction" mode :)
Sounds like a Frontier. Though they will load a TIFF image, there are a
lot of restrictions as to what the lab can accept. It's easier for them
to say "JPEG only kthx" than give a huge list of methods for making
acceptable TIFFs.
Considering the fact that I used 1950 patches, I should still be able
to generate good medium quality profiles from the charts, right?
Should be fine. I printed out a bunch of standard RGB charts from the
SpyderPrint software and calibrated with them, no problems. Admittedly
that's not Argyll, but I'd expect the same sort of rules to hold...
--
Phil.
philpem@xxxxxxxxxxxxx
http://www.philpem.me.uk/
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