Hi Cody,
I had something similar come up a few years back. Had made a print for someone
on my Canon 9500 II. It was a quick print from their sRGB image letting the
printer manage colors. They then wanted a larger version but with as close as
possible to an exact match of the colors that the 9500 II had printed.
This turned out to be difficult because my larger printer is an Epson 9800 and
the 9800 printer produced notable less saturated prints. Now normally I print
with color managed workflow, not the quick and dirty way I had originally made
the guy’s print.
So I investigated what was going on with the 9500 and it turned out that the
perceptual mode letting the printer manage colors greatly increased saturation
in many areas. Also, many were substantially increased in brightness. Over 10
dE in many areas and even well outside sRGB’s gamut. Apparently this is done by
the 9500’d default to create more pleasing, colorful images from typical
snapshots.
So, having printer profiling hardware, I found a solution which is to
characterize the 9500 II’s default gamut mapping by making a special purpose
profile. It worked perfectly. Here’s what I did.
1. I created a set of patches and tif files as normal to profile a printer
but instead of printing w/o color management, I assigned the patches to sRGB.
Then printed the targets on the Canon 9500 II using the exact settings (printer
manages colors) used when I had initially printed the guy’s image. And then
from this printed target I made a profile I called “simulation9500.icm”
2. Then, with a copy of the original image the image was assigned to
“simulation9500.icm” Note that this profile is not and should not be used for
normal printing. After assignment then the image should be converted to the
desired colorspace using Relative Colorimetric without BPC. I used ProPhoto RGB
but any standard RGB colorspace can be used if the colors don’t exceed it.
Adobe RGB (1998) would probably have been just fine.
3. Now, the image is printed using using standard color managed workflow
with Relative Colorimetric AND a custom Epson 9800 profile made by the same
spectrophotometer/software. The result was a match. At least for all colors
that are within the 9800 gamut
Give it a shot.
From: argyllcms-bounce@xxxxxxxxxxxxx <argyllcms-bounce@xxxxxxxxxxxxx> On Behalf
Of Cody Ranaldo
Sent: Wednesday, August 5, 2020 10:12 AM
To: Argyllcms <argyllcms@xxxxxxxxxxxxx>
Subject: [argyllcms] Re: Visual Match of Two Printers
Thanks everyone for your responses-- I've experienced essentially the same
thing as Graeme when it comes to having multiple printers of the same type
being run through the same RIP-- Especially when you are defining ink limits
individually. One thing I didn't go over in my original post was that I was
able to calibrate an Epson 9880 using the same everything as the 11880 I was
trying to match (except for the spectro) and I was able to get a very close
match. I don't doubt that it would have been even better had I been using the
exact same measuring device to profile both printers.
I guess what I'm ultimately looking for is something slightly different, and it
relates back to the first time I posted about this: some kind of way of
fingerprinting a printer's current output "style" to simulate it on another
printer-- regardless of RIP, CMM, ink limiting setup, age of profile, or
printing color mode (RGB, CMYK, N-color..) etc.
A situation I find myself in often is receiving a small test print from a
client, who loves the color of what they were able to obtain on their home
setup, but they know nothing about color management. Most likely they are
using a canned profile, and maybe not even the correct one for the correct
paper. Then they want me to be able to exactly match that print in order to
make a larger version of it. This generally leads to a large amount of back
and forth (depending on how anal the client is) and a lot of manual tweaking of
colors in the file and many iterative prints to get to a closer match. The
situation I'm in right now is similar-- only in that the printer being used to
make my match print is an older model than the one I have currently, and the
client is exacting to the point of near-insanity. I've had clients before
reject prints because they were printed on the left side of the printer as
opposed to the right, and I've had clients complain of differences in two
prints that came out immediately after one another in the same exact spot
seconds apart (THAT particular conversation is one of psychiatry).
But I've been doing a lot of thinking about this, and it seems like something
like this should be possible essentially using the tools we use for calibrating
input devices (cameras and scanners). Essentially, a target having known
values, like a colorchecker only with far more patches would be printed using
whatever color management setup is present, which could then generate a 3D LUT
or abstract ICC profile which could be applied to the file manually, even as a
layer in photoshop, which would then alter the colors in the image before going
through a tightly calibrated system. As long as the gamut of the reference
system is sufficiently larger than the target, or the images are not containing
colors that push the boundaries of the gamuts, it should be possible to
simulate the conditions of any machine in any specific state...
The main issue I think I've been dealing with concerning the p20000 and the
11880 is the black depth of the matte black ink-- the images I'm printing have
very deep blacks which are shown to be out of gamut, and the two printers have
different min L* capabilities on matte paper.
When I get the chance I'm going to experiment using the input calibration tools
in argyll to see if I can make this into something workable.
-------
Profile Printer A, and profile Printer B using an instrument you trust.
Create a proofing transform (i.e. device link ?) from printer A to
printer B. Print (or color transform) your images as if you were printing
to printer A, but save the output to a raster, and then transform
it to Printer B space using the proofing transform. Print on
printer B using no color management.
An alternative to creating the proofing transform is simply to take
your Printer A raster from above and print it to printer B using the Printer A
profile
as the source profile (and printer B's profile as the destination profile).
Use relative colorimetric intent.
The other times I tried to use the same technique, the results were not very
good.
Break down of the theory? I'll never know. But it was pure hell.
