Yves, Alan, List,
Moi aussi, je réfléchis à une méthode objective dévaluation.
There has to be a difference between image-gamut based conversion and
color space or specific color space conversions. The difference,
however, is not easy to analyze.
(Have to give it better thought
)
I am running into the same problem as Yvess original issue, what is it that
were getting (presumably of extra value) when creating custom-tailored
printer profiles in Argyll?
As some of you may know, Im experimenting with Epson EnhanceMatte paper
these days, on my humble inkjet printer, and, the moment, I am in the final
stage of characterizing the whole thing with an IT8.7/4 target in my hands,
ready to measure and generate an Output profile for.
Q1: do I want to flip the switch on some Source space optimization? Such
as sRGB -> EnhanceMatteCMYK?
Q2: Once I do, how do I go about finding the difference?
I figure Im going to need to create some kind of synthetic image to be able
to make the differences come out? My take is that A) colors that are already
well within gamut, such as skintones, blue skies, most foliage and grays are
all going to be mapped pretty much 1:1 but B) colors that are out-of-gamut
have to suffer some kind of compression.
I think I remember seeing some visualization of this? But Id like to see in
on a graph, in Excel. Love Excel
.
Best / Roger
From: argyllcms-bounce@xxxxxxxxxxxxx <argyllcms-bounce@xxxxxxxxxxxxx> On
Behalf Of Yves Gauvreau
Sent: Saturday, July 6, 2019 6:33 AM
To: argyllcms@xxxxxxxxxxxxx
Subject: [argyllcms] Re: Testing my new printer
Alan,
my printer is the same as yours (Pro-1000) and I used a letter size sheet of
Hahnemuehle fine art baryta paper. I use the same test or standard image as
you do every time I want to have an idea of what a paper can give me. Now I
do this part a bit differently to save ink.
In the docs it is mentioned this: "When images are stored in large gamut
colorspaces (such as. L*a*b*, ProPhoto, scRGB etc.), then using the
colorspace gamut as the source gamut for gamut mapping is generally a bad
idea, as it leads to overly compressed and dull images. The correct approach
is to use a source gamut that represents the gamut of the images
themselves." Since I print just as you do most of the time, from Lightroom I
wondered if my prints where impacted in the way the doc mention because
Lightroom uses the ProPhoto RGB colorspace by default, and because this
effect seemed to be barely noticeable on the relatively large gamut papers I
use most of the time. I notice thought that on some papers with a smaller
gamut, the result are much less interesting or kind of dull but again all
this is subjective.
I'm not sure but I think Graeme mentioned to someone about his method that
folks at Adobe for example may very well do something similar without
letting you know about it. I know that Adobe is adding a curve to there
Adobe Standard profile on each raw conversion Lightroom or ACR does, it
makes the image "look" better but at the expense of dynamic range
(reduction) and many times it increases clipping of the highlights and it
also reduces highlight details in many case.
So I wonder if someone here as a method or suggestion of evaluating all of
this more objectively and or accurately then just comparing standard prints
visually?
Yves
On 7/5/2019 8:42 PM, Alan Goldhammer (Redacted sender agoldhammer for DMARC)
wrote:
You do not say what the make of the printer is and what type of paper you
will be printing on. Most RGB printers are well behaved and I do not see
the need to use exotic approaches to printing. I print directly from
Lightroom on my Canon Pro-1000 as it is the most convenient way to print as
one only needs to set things up once and then save the preset. I do my
profiling using Argyll for the papers I print on. I evaluate profiles
visually using this test print:
http://www.outbackphoto.com/printinginsights/pi049/essay.html which has
various standard images that have been used for some years now. I do soft
print in Lightroom but only to correct for certain colors and hues as soft
proofing for out of gamut colors is notoriously poor.
Alan
From: argyllcms-bounce@xxxxxxxxxxxxx <mailto:argyllcms-bounce@xxxxxxxxxxxxx>
[mailto:argyllcms-bounce@xxxxxxxxxxxxx] On Behalf Of Yves Gauvreau
Sent: Friday, July 5, 2019 6:16 PM
To: argyllcms@xxxxxxxxxxxxx <mailto:argyllcms@xxxxxxxxxxxxx>
Subject: [argyllcms] Testing my new printer
Hi,
I started testing my new printer with an image that as colors outside the
gamut of the paper as per ColorThink 2.3.3 to see if there would be a
benefit in using the "Image dependent gamut mapping using device links
<https://www.argyllcms.com/doc/Scenarios.html#LP3> " method and printing
from Photoshop and I don't see any difference at least visually. I know
this is amateurish to say the least.
So is there a mean to evaluate this process (using the image gamut) more
"properly" and more exactly?
Thanks
YG