Yves,
The two graphs shown in “Figures 79” were made from the *same* profile, one
with AbsCol and the other with RelCol.
Here’s the original text:
As this is not a proofing exercise for measuring dE values, one may implement
this test using different Rendering Intents (RI) to see what difference they
make to predicted outcomes for real-world photographs. I have chosen to use two
RI – Absolute Colorimetric (ABSCOL) to see how the printer reproduces
unadjusted file values (as in proofing) and Relative Colorimetric (RELCOL) +
Black Point Compensation (BPC) to see how the printer reproduces adjusted file
values per the standard RELCOL +BPC rendition in Photoshop. Normally we print
real photos with either Perceptual or RELCOL, not ABSCOL, so it’s important to
see what RELCOL or Perceptual would do to the appearance of shadow detail in a
printed photo. I chose to work with RELCOL + BPC, as it does less shifting of
in-gamut values and many prefer this RI. I could rerun these tests with
Perceptual RI, but in light of my findings below, I think perhaps not really
necessary. The usual advice for printing is to try both.
Figures 79 and 80 show the graphs for ABSCOL and RELCOL respectively.
/ Roger
From: argyllcms-bounce@xxxxxxxxxxxxx <argyllcms-bounce@xxxxxxxxxxxxx> On Behalf
Of Yves Gauvreau
Sent: December 16, 2019 12:13 PM
To: argyllcms@xxxxxxxxxxxxx
Subject: [argyllcms] Re: Can we control the shadows (was black point
compensation)
Here a link to a copy of the page and hopefully all the images and what have
you, it's also a Mark Segal article.
(https://www.dropbox.com/s/4q4tnu4pkowhaep/test.zip?dl=0)
I guess I'm not the only one not to read every thing that is thrown at me LOL
I agree with you that it would be instructive as I already did read it. I just
verified, and figure 79 image is in the folder so everyone should see it.
I'll repeat how those graph where made, both have the same original test image
( grey patches with L* values from 1 to 30), so same input, same printer, same
paper, etc. The only thing different is the "profile", the one used for the
left graph was printed with a profile done without using the M3 filter and for
the one on the right, a profile made with an M3 filter.
This kind of prove that "good" profile can be made at minimum using an M3
filter instrument.
Can we trick a profile to give us results as if it was made with a M3 filter?
If so how to proceed with Argyll of course?
Yves
On 12/16/2019 11:27 AM, Alan Goldhammer (Redacted sender agoldhammer for DMARC)
wrote:
I think you are asking too much of the profile when you should be focusing on
image processing. I’m pretty sure I posted this already:
https://forum.luminous-landscape.com/index.php?topic=118349.0 There are four ;
pages of discussion about the Chromix made profile and from users such as
myself. On page three, Graeme weighs in on the use of M3 measurements. Doug
Gray and Mark Segal (the author of the paper review) who both have done lots of
profiling also weigh in on this. It would be instructive to read that. If you
are content with the high gamut Chromix profile, why don’t you just use it
rather than trying to use Argyll to create a profile that won’t give you the
same type of result. You won’t be able to replicate what Chromix has done with
your hardware.
I let my subscription to Luminous Landscape lapse as I no longer found the new
articles of any interest so I cannot access the figure you mentioned.
Alan
From: argyllcms-bounce@xxxxxxxxxxxxx <mailto:argyllcms-bounce@xxxxxxxxxxxxx>
[mailto:argyllcms-bounce@xxxxxxxxxxxxx] On Behalf Of Yves Gauvreau
Sent: Monday, December 16, 2019 10:09 AM
To: argyllcms@xxxxxxxxxxxxx <mailto:argyllcms@xxxxxxxxxxxxx>
Subject: [argyllcms] Re: Can we control the shadows (was black point
compensation)
I'm not trying to print darker blacks, on whatever paper. This would be a
humongous waste of time and resources.
I obviously don't use the same language as you guys it would seem.
On figure 79 on the left side in particular, for any input below L* 12 the
output or print value I get is the almost the same at L* just above 16 (that's
bad, a waste, etc). What I want is a way to make a profile that would print for
the same input as on the left side, a response or a print value that increase
as much as possible relative to increases in input values, just like on the
graph on the right side of figure 79.
Regards,
Yves
On 12/16/2019 9:41 AM, Alan Goldhammer (Redacted sender agoldhammer for DMARC)
wrote:
Printer manufacturers write drivers tailored to the papers they sell. In many
cases the papers are re-branded from major suppliers. Unless you purchase a
RIP, you are hostage to what the printer manufacturer provides. Sometimes they
will update firmware and drivers as Canon recently did for Barayta papers,
providing a new setting that can be used. With my old Epson 3880 there were
driver tools to adjust ink density within some limits. I’ve not looked at my
Canon Pro-1000 to see if the same feature is available. Even with the Epson
settings, I never found that I had to do any adjusting and of course one will
have to reprofile everytime ink densities are changed to deal with potential
color shifts.
Some years ago, Scott Martin provided a nice test chart that allows one to look
at various paper settings and pick the best setting. As he says, “Compare the
final prints for maximum black density (DMax), color gamut, shadow detail and
dot smoothness. You’ll want to choose the media selection that delivers the
best DMax without losing a significant amount of shadow detail (loosing 5% or
less is OK), or without a course dot pattern caused by what I call “micro
pooling” (where dots touch due to excessive ink).” You can find the print
chart and further information here:
https://www.on-sight.com/how-to-determine-the-optimal-media-selection-for-any-paper/
this does what Greg describes in his email response to Yves. I’ve used this
chart over the years every time I try out a new paper. In all but one case, I
found the paper manufacturer’s suggested settings to be the best one.
Ultimately, bringing out shadow detail is really a function of the digital
image processing. As I noted earlier and provided some good references, soft
proofing is a key part of this process. What you see on your computer screen
in the absence of soft proofing is misleading as the screen gamut can be quite
different from the paper’s.
Alan
From: argyllcms-bounce@xxxxxxxxxxxxx <mailto:argyllcms-bounce@xxxxxxxxxxxxx>
[mailto:argyllcms-bounce@xxxxxxxxxxxxx] On Behalf Of graxx@xxxxxxxxxxxx ;
<mailto:graxx@xxxxxxxxxxxx>
Sent: Monday, December 16, 2019 8:43 AM
To: argyllcms@xxxxxxxxxxxxx <mailto:argyllcms@xxxxxxxxxxxxx>
Subject: [argyllcms] Re: Can we control the shadows (was black point
compensation)
Thank you Greg. That’s the point I was trying to drive.
I know that “more ink volume” does not “necessarily” translate into “higher
dmax”, I know. There is a point of “diminishing returns”, just as in
micro-economics. Your suggestion to use a small chart is right on the money.
/ Roger
From: argyllcms-bounce@xxxxxxxxxxxxx <mailto:argyllcms-bounce@xxxxxxxxxxxxx>
<argyllcms-bounce@xxxxxxxxxxxxx <mailto:argyllcms-bounce@xxxxxxxxxxxxx> > On
Behalf Of Greg E
Sent: December 16, 2019 8:38 AM
To: argyllcms@xxxxxxxxxxxxx <mailto:argyllcms@xxxxxxxxxxxxx>
Subject: [argyllcms] Re: Can we control the shadows (was black point
compensation)
In the past I ran a printer on a real RIP, had control way past normal ink
volumes. More ink does not equate to darker dmax. In reality once you go too
far, the dmax starts to get lighter again. Doesn't really answer the question
of what the Canon driver will let you send.
Also in the past, helping other people with their profiling, we would have them
print a small chart using several different printer settings, selecting
different types of paper in the driver. Then you measure all the samples to
find the one that gave the best results and print the larger profile target.
Since we don't have control over ink limits, this is about the only way to vary
the amount if maximum ink on paper.
