[argyllcms] Re: Spyder4: Difference in using argyllcms and original software

  • From: Werzi2001@xxxxxx
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Thu, 12 Nov 2015 00:01:25 +0100

Hi Ben,

thanks for your extensive answer.

You are definitely right. I'm not sure what actually would be the
correct result and as a software developer i know very well that "looks
different" is a very bad description ;-) I am just confused that the two
calibration programs (original software and ArgyLL CMS) seem to result
in completely different results even when using (at least as far as i
know) the same parameters (gamma, white point, hardware). I would have
expected to get at least somehow identical results.

The problem is that i really can't tell which of the results is the
right one. My goal is to have the colors somehow match the colors when i
print the images (or letting them print by a printing service). For my
last prints i noticed that the colors weren't really correct (colors on
laptop seem to be missing red colors and seem to be too dark). They were
acceptable but there must be a way to get it more accurate.

Maybe the goal can not be achieved by a simple calibration. I'll
definitely have to do further researches about that.

Just one more thing i've tried:
In dispcalGUI there is the possibility to "check" the current profile
and get some kind of report as a HTML page. Here is the result of my check:
http://www.xup.in/dl,39325286/checkresult.html/

Again maybe this isn't the right way to check the results but at least
from my newbie perspective it seems that the results aren't really good
(too much red checks and color differences).

Best regards
Werzi2001

On 11.11.2015 23:45, Ben Goren wrote:

On Nov 11, 2015, at 3:01 PM, Werzi2001@xxxxxx wrote:

The result did change a bit but not in the way the original software
does.
It's worth questioning what your goals are. Do you have an objective means of
determining the quality of the results? "Looks different" covers a lot of
stuff, and it could well be that the change the original software made wasn't
necessarily for the better.

For most people, the end goal is to match a certain white point, either a
particular absolute standard (usually 6500K for Internet and broadcast and
5000K for print) or the ambient lighting conditions -- and similar concerns
for absolute brightness. Once that's achieved, the next goal is colorimetric
accuracy such that the displayed colors are as close as possible to the
(white-point-adapted) absolute colors referenced by digital files. And,
finally, you're typically looking to maximize detail and minimize artifacts,
which is, again, achieved by accurate color reproduction.

So, you can use the instrument to measure the final white point if you trust
the instrument. If you've used the instrument to match ambient conditions,
you should be able to hold a piece of PTFE (Teflon) thread seal tape up to
the monitor with a white background, and the two should be the same color and
perhaps the same brightness. If you've done that, you should be able to do a
similar comparison with a reference chart such as a ColorChecker. If that
checks, you can examine various reference files; see, for example, how well
fine details in a photo of un-hewn granite are discernible, and look for a
lack of smoothness in a Grainger Rainbow.

There're lots of ways to evaluate a display profile; I'm just hinting at how
to scratch the surface here. But "looks different" isn't necessarily the most
sophisticated method....

b&


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