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 dayC) 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/