Roger,
I started from targen, printarg, etc.
I also reduce the number of patch (722) to 2 sheets instead of 3 (1083)
just in case it would be just a waste of paper again. Seems I did
something wrong and unfortunately I can't figure out what it was.
I think I have a useful profile and I can restate my original goal for
doing all this. I trying to obtain a print that "looks" as much as is
possible to the original image on my display. The usual method of doing
this in Photoshop doesn't seem to be adequate as the print are even
darker and flatter contrast wise then the softproof would suggest. The
image dependent method seem to provide a much better "looking" softproof
version but when I print the image it is still not as "good" looking as
my display.
Maybe it's not possible to achieve better results via profiling software
as Graeme suggested. I understand the ultimate best way to get the
result I want is on a per image basis and I would like to find a method
that is as objective as possible.
Thanks to all for their patience,
Yves
On 12/9/2019 1:41 PM, graxx@xxxxxxxxxxxx wrote:
Did you “reprint” the target?
Or did you simply “re-measure the same printed target”?
Whatever you did, you’re on the right track!
Your perseverance paid off.
/ Roger
*From:* argyllcms-bounce@xxxxxxxxxxxxx <argyllcms-bounce@xxxxxxxxxxxxx> *On Behalf Of *Yves Gauvreau
*Sent:* December 9, 2019 12:10 PM
*To:* argyllcms@xxxxxxxxxxxxx
*Subject:* [argyllcms] Re: Something is wrong
Still don't know why but I started from scratch and got much better results.
profcheck -k RR_PaloDuroSGR_PRO1000.ti3 RR_PaloDuroSGR_PRO1000.icm
Profile check complete, errors(CIEDE2000): max. = 1.504325, avg. = 0.417007, RMS = 0.479644
That seems very good!
Thanks,
Yves
PS I'll try this idea of measuring multiple times to see if I can get even better results.
On 12/9/2019 11:13 AM, Yves Gauvreau wrote:
Roger,
On 12/9/2019 7:22 AM, graxx@xxxxxxxxxxxx
<mailto:graxx@xxxxxxxxxxxx> wrote:
Yves,
In general, to get the best results possible, should we
just pruned out
these
outliers? Would taking multiple measures of the patches
and use the
average
or the "median" be a good practice or just a waste of time?
You need to understand what you're doing. In the context that
the device
(paper) is highly non-linear, *all* the patches are important
to build a
model of the output.
Lut base profile are so sparse that it's impossible to capture the
fine details of this non-linearity you speak of. I don't know how
the CMMs compute their output when they need to interpolate
between grid points but I doubt it is in a non-linear fashion. I
believe these Lut are in PCS space, so gamma = 1.0 and I wouldn't
be surprised if the interpolation was basically linear as well.
Outliers are always a nuisance IMHO.
Is there a way you can start with a tiny patch set? Instead of
the full
1000+?
That way, less chances of errors. I seem to remember, a long
time ago, that
Argyll was able to make profiles from as low as 60 some
patches. If that was
still the case, you could make all the measurements one at a
time (if the
software allows manual reading) and analyze each patch. You
need to better
understand what you're measuring to be able to tell if there
is something
wrong with the generated profile. That's what I do. You have
to understand
the underlying device behavior from the measurements.
/ Roger
Maybe I don't understand what you mean but I would believe a more
robust approach then a patch by patch one, would be to measure all
the patches several times and use "average(.exe)" to sort out
which of these measure we will actually use (average, median or a
Geometric Median). This should improve our chance of obtaining a
measure that is closer to the real thing. Your approach, sound
nice, but choosing a measure just because it's closer to the
target isn't good practice IMHO, there is nothing to say that this
measure is the best one or the worst for that matter. Maybe the
printer is way off for this particular color or maybe it's an out
of gamut color and the "best" measure should be farther away for
this or that particular target.
Yves
