Dear Roger:
Linear response curve in Capture One doesn't mean that the TIFF is in gamma 1.
So, the question is: will Argyll compute a reasonable matrix profile using a
TIFF that is not linear?
Capture One expects LUT-based camera profiles, and will provide most of the
functionality using matrix profiles with gamma 1.8.
A LUT-based profile from 18 colour patches made using 4 or 5 spectrally
different pigments is IMO not very useful.
Accurate capture of the target (low flare, flat-fielding technique) help to
decrease profiling error a lot. That's the first resource to improve profiles.
Max dE2000 < 6 means a very good profile. 8 is acceptable.
On Jan 19, 2021, at 3:14 PM, <graxx@xxxxxxxxxxxx> wrote:
In Argyll’s excellent online documentation, with regards to colprof, we find :
“ The -am option will create a matrix profile with linear (i.e. gamma = 1.0)
curves. This may be useful in creating a profile for a device that is known
to have a perfectly linear response, such as a camera in RAW mode.”
I created a digital camera profile for my Nikon camera, based on a TIFF
exported out of CaptureOne (with Linear Response curve).
I confess I’m rather “new” to camera profiling.
I was looking at the “statistics” line :
“Profile check complete, peak err = 8.409639, avg err = 2.301651“
So this means 8.4 DeltaE as the largest error and an average of 2.3 DeltaE?
Out of 24 patches?
I wanted to convince myself that the largest error was indeed 8.4 DeltaE, so
I manually took “reading” with the color picker in Photoshop, having
converted the image from the Argyll profile to Lab using AbsCol and got :
https://1drv.ms/u/s!AkD78CVR1NBqlrl0s9TCgXleuRqxsw?e=0aq60R
The peak error, as far as I can see through this method, is on the ORANGE
patch, a 7.53 DeltaE.
Is there a way to improve the profile? Would another type of profile work
“better”?
/ Roger Breton
From: argyllcms-bounce@xxxxxxxxxxxxx <argyllcms-bounce@xxxxxxxxxxxxx> On
Behalf Of graxx@xxxxxxxxxxxx
Sent: Sunday, January 17, 2021 8:14 PM
To: argyllcms@xxxxxxxxxxxxx
Subject: [argyllcms] Re: Digital Camera Profiling from ColorChecker 24
Found the culprit 😊
https://1drv.ms/u/s!AkD78CVR1NBqlrlw81DJ6sZtI3dZ8Q?e=gkm3on
Much better.
I had the patches in the wrong order in the measurements file.
/ Roger
