[argyllcms] Re: Camera matrix profile, adding ti3 perfect white data set

  • From: Ben Goren <ben@xxxxxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Fri, 22 Jan 2010 10:03:03 -0700

On 2010 Jan 22, at 9:56 AM, Iliah Borg wrote:

> Dear Klaus,
> 
>>> For more complex profiles the only method that I know
>>> working is projecting the rainbow from a diffraction
>>> grating onto the sensor.
>> 
>> Sounds exciting to me. Can you give us further details
>> (e.g. how to obtain the target values)?
> 
> The simplest method is to sandwich the grating with an
> aperture (narrow slit), to read the opening with a
> spectrophotometer, and to expose; next, to move the
> aperture and repeat. Adding some stepper to move the
> aperture in a consistent and repeatable way does not hurt.
> This way all the readings can be done in advance, given the
> light source is suitable. In essence the automation is a
> rework of a desktop scanner. Multi-aperture schemes usually
> faster but less accurate.  

Any chance you can post a picture of your setup, and perhaps a parts list?

If I'm understanding this right, since you're essentially profiling a target 
with (almost) monochromatic light sources, wouldn't that imply that one should 
be able to do the profiling with a linear RAW conversion with no white balance 
applied? White balance adjustment of actual pictures would then be a matter of 
converting to a profile with the desired white balance, no?

Cheers,

b&

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