[argyllcms] Re: help with camera profile

  • From: Ben Goren <ben@xxxxxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Wed, 25 Jul 2012 09:23:16 -0700

On 2012-07-25, at 8:29 AM, Iliah Borg wrote:

> With digital there is no simple way to get density or L* values, and 
> linearization in RGGB domain does not work too well.

If you're using Adobe Camera Raw or something else that works with DNG 
profiles, you can (awkwardly) create a DNG profile with a custom tone curve. 
Shoot a target with known Lab values, and then adjust the tone curve until the 
output matches the measured values. On a Mac at least, you'll need Adobe's DNG 
Editor and the Digital Color Meter application. If, while you're at it, you 
also use DNG Editor's feature to create color tables from a ColorChecker, the 
resulting output is already decidedly in the ``not bad'' category. Profile 
those results with Argyll, and you get great results.

RAW Developer would seem to make that process a bit easier as it lets you edit 
the tone curve right there, and it gives you much more helpful pixel readouts. 
What I suspect I'll be doing, at least for the time being, is creating a tone 
curve that maps the neutral step patches to the corresponding RGB values for 
the gamma of whatever working space I feel moved to use this week. (I've been 
using ProPhoto RGB because that's been the least awful one that Adobe lets you 
convert RAW to, but I'll probably move back to Beta RGB with RAW Developer.)

What I'm envisioning for Argyll is a modification to scanin such that it still 
takes an RGB TIFF but then calculates the calibration curves at the same time 
as it reads the patch values. You could then feed it a linear TIFF output if 
your RAW developer supports such, or whatever else you can manage, and let 
scanin be the one to worry about the tone curve.



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