Message
Re: [colorvision_group] Re: Using Colorimeter to evaluate and edit profiles??
2008-05-12 by CDTobie@aol.com
In a message dated 5/12/08 2:18:00 PM, rschoner@... writes:
Thanks again for the follow up.
First, the easy question: What Printer? This is an Epson R1800 with
an InkRepublic Continuous Ink System and Image Specialists inks.
Although it has two black inks, Photo Black and Matte Black, I think
it only uses one ink at a time depending on the paper/media setting.
So, I guess that makes it a "one black" printer. It has Cyan, Yellow,
Magenta, Red and Blue for the colors. No more Photo Cyan or Photo
Magenta.
Okay, the R1800 is a great color printer, but absolutely not a black and white printer. It has no gray inks at all, and all of its grays are generated from color inks... and not evey light tone inks, full density color inks. That would explain your issues...
One observation from this process--the measurements change with time
and location. The largest variations come just after the chart is
printed; a drying effect I guess.
Yes, there are drying effects, but even with great patience and great care, the R1800 is just not going to print great black and white images; any change in the light source will cause significant changes is the percieved tone of grays formed from color inks; so your B&W images will be green in one light and pink in another.
But, I do notice a change
overnight. One example: 47.57, 4.39, 0.54 went to 48.77, 3.69, 1.60.
Do you have a feel for what acceptable measurement variation is?
While its still changing whole numbers, its not dry yet; but as I note above, the R1800 is not going to produce gallery quality B&W no matter how exacting you are.
Your suggestion to back up the measurement charts with extra paper is
very good. I notice a variation if I do not back up the paper. I also
notice some variation within the measurement patch, I guess that's
the printer/ink.
I tried the PhotoShop ACV curve correction process but did not have
good luck. I used the R channel since the image had a pinkish cast
but the error was so slight a small adjustment fixes the SoftProof
but the print is not correct. I tried assigning the printer profile
to the test image and then "auto correct" with the curves layer but
that's disastrous. I guess that's why I asked about a LAB correction
option in Spyder. BTW, I find the SpyderProof "exagerates" the
errors/correction compared to PhotoShop or QImage soft Proof.
Probably because it factors in ink black and paper white. If you check those boxes in Photoshop, results should be equivalent.
Sorry for the long post but, in spite of the effort involved, it is
still fun. Just wish I knew more.
Well, you may know something now that you didn't previously. An R2400 would produce gallery quality, visually stable B&W prints (as would a 3800, a Canon iPF5000 or a Pro9500) but the R1800 is aimed very much in the other direction: glossy color prints. Which is not to say you can't improve your B&W results, just that they won't ever be stable enough to do gallery quality B&W.
Sorry to be the bearer of bad news...
C. David Tobie
WW Product Technology Manager
Digital Imaging & Home Theater
Datacolor
CDTobie@...
www.datacolor.com/Spyder3
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