[argyllcms] Re: Mini color checker WAS: Generated camera profile too bright

  • From: János, Tóth F. <janos666@xxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Wed, 25 Apr 2012 02:15:48 +0200

Noob question!

By the way, what is the correct way to convert from RAW to TIFF?

I mean, there is a white color temperature and a huye control for the
white point in both PhotoShop CS5 and UFRAW (Gimp plugin).

1: Is it OK to measure the actual light in the room with a spectro
(using the ambient light diffuser), use the CCT value (and zero huye
adjustment) in the software and create a profile which doesn't map the
WP to D50?

2: Is it OK to set the WP to 5000K (or anything random) in the
software (even if it's not correct), create a standard ICC profile and
use absolute colorimetry in the software later (with the same false
software WP setting)?

Which one is preferable?

If I create a non-standard absolute profile then can I use that for
photos taken under different ambient light in case I set the actual
CCT in the software? Or is the differen light (different spectral
characteristics, like fluorescent tubes intead of daylight...) makes
that profile useless anyway? (I guess so.)
I mean... Is that profile still better than „no profile” (whatever the
software assumes when I supply nothing).

Problem: I am not a photographer, I just use my camera randomly. But
if I have a spectro and the camera supports RAW anyway then I wish to
make some use of the possibilities...

I already tried to create some profiles but they were never good enough.
I mean they caused some obvious color errors and the default color
matrix looked more neutral (but far from perfect).

2012/4/24, Andreas F.X. Siegert <lists@xxxxxxxxxxxxx>:
> On 03.04.2012 09:00, Graeme Gill wrote:
>> Maybe there's something about how your workflow converts
>> from RAW to .tiff that is a problem ? Maybe it's not scaling
>> the RAW numbers to the full 16 bit .tiff range ?
> That turns out to be the case, AS currently has a bug here where 14bits
> are just put into 16...
> Ok, so using an exposure boost of two stops in linear should do it....
> But, at http://afximages.com/tmp/argyll
> I have two NEFs:
> _AFX9383.NEF
> from this I can generate a profile easily everything is fine and dandy
> (not that think the profile is perfect, but it shows that the process works)
> and then _AFX9580.NEF
> scanin will only accept this when it is overexposed which of course
> leads to a dark profile....
> Why?
> Could it be that I am too optimistic with my attempts to use the
> Colorchecker reference files for a mini color checker?
> thx
> afx
> --
> http://afximages.com/

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