[argyllcms] Re: Fwd: Simple how-to on camera profiling

  • From: Karljohan Lundin Palmerius <karljohan.palmerius@xxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Thu, 18 Mar 2010 08:19:02 +0100

>> I'm a "user" of colour profiling but not very knowledgeable, but I
>> finally think that I've managed to put bits and pieces together to
>> define a work flow for creating a settings specific colour profile for
>> a camera. I've written a how-to on this to help others in my
>> situation. I welcome anyone to comment on the procedure and chosen
>> parameters. It should be noted that I use QPCard201 which has a
>> relatively small set of colour patches and so can't be expected to
>> suffice for a detailed colour profile.
>> http://staffwww.itn.liu.se/~karlu/div/howto/cameraProfile.php
> For which RAW converter are you profiling?

I use UFRaw. Actually, I've never tried anything else but it seems to
fit my needs.

>> To facilitate the process of extracting the target's colour patches,
>> I've implemented a GUI for marking the "fiducial square" to get the
>> coordinates to put into scanin. I could not find anything like it so I
>> just had to implement my own. It's a bit of a hack, but features
>> rendering of the target geometry which is very useful, especially if
>> the target is not entirely flat so that the geometry has to be
>> tweaked.
> Doesn't scanin autodetect this? It should...

As far as I understand scanin is capable of finding the target as long
as it is large on the image and only subject to affine transforms.
This is not the case in photography.

Also, with "not flat" I mean that the actual target can be slightly
bent after storage in a camera bag. In that case the automatic
matching using computer vision will have a very hard time determining
the correct geometry even if it supports projective mappings.

> With low patch count targets I'd stick with matrix only profiles...

I tried -aS and -ag as suggested by Nikolay before, but got poor
results with -aS, so in the how-to I suggest -ag which is
gamma+matrix. I did have some trouble also with -ag at the time I
decided to not use -aS so the problem with -aS could have been caused
by some other problem in the pipeline.

/ KJ

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