There are many ways to evaluate the smoothness of an ICC profile.
I would start, first, by evaluating its DeltaE conformance to the original
measurements.
There are utilities that allows examining the data points of an ICC profile
in 3D.
They allow to display the data points and rotate them around the Lab axis.
Any discrepancy is immediately visible.
/ Roger Breton
-----Original Message-----
From: argyllcms-bounce@xxxxxxxxxxxxx [mailto:argyllcms-bounce@xxxxxxxxxxxxx]
On Behalf Of Jarkko Lavinen
Sent: Wednesday, August 30, 2017 11:16 AM
To: argyllcms@xxxxxxxxxxxxx
Subject: [argyllcms] How lumpy is the LUT produced by colprof?
Hello
Is there a way to evaluate profile lumpiness? Applying a profile and seeing
or suspecting to see weird colors one. I was thinking if an interpolation
between patches could reveal excessive color or luminance drift.
There is a smoothing option -r (and -rr, rs) in colprof but ti3 file does
not seem to carry individual patch XYZ noise stats and the smoothing figure
likely does not depend on how reliable the patch XYZ reference data is.
Could this exaggerate bumps with noisy patch XYZ reference data?
I was initially using Vuescan with IT8 calibration and scanning slides and
thought everything was fine. Then I learned Vuescan supports only its own
matrix profiles and they suck and LUT profiles are supposedly so much better
[1] [2]. And then finally I learned LUT profiles suck too [3] [4].
Oldendorf is the author of ColorPerfect PhotoShop plugin. He talks about
color integrity being fragile and being destroyed by non-linear
transformations. In [3] he says: "Lookup tables are completely unsuitable
for RGB input devices.". In [4] he criticizes many thins but LUTs are
criticized for their lumpiness and breaking havoc. Is this FUD?
Jarkko Lavinen
[1]
http://blog.iansheh.com/2012/01/vuescan-how-to-profile-your-scanner-film/ ;
Vuescan: how to profile your scanner/film
[2]
http://blog.iansheh.com/2013/04/how-to-get-the-best-scans-from-vuescan-profi
ling-scanning/
How to get the best scans from Vuescan (profiling & scanning) [Updated]
[3] https://www.flickr.com/groups/977912@N23/discuss/72157642609040454/
ColorPerfect Workflow with ICM
[4] http://www.c-f-systems.com/Complete/CalibratingDigitalImages.html
Comments on Calibrating Digital Images
http://www.c-f-systems.com/Complete/CalibratingDigitalImages.html#Pitfalls
The Pitfalls of Using Profiling as Camera Calibration
