[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 02:24:47 +0200

Oh, I forgot:
I need to set something as input and output profile during the
conversion of the colorchecker photo.

3: Should I set the input to „no profile” and the output to anything?

4: Should I set both to the same profiles? (Is it OK to use any kind
of profile in this case?)
Will ArgyllCMS use the embedded profile?

What the software will assume with „no profile” input settings? Will
it convert to the outout profile anyway (using some assumptions) or
will it simply save the RAW values of the sensor channels as R, G, B?

2012/4/25, János, Tóth F. <janos666@xxxxxxxxxx>:
> 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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