[argyllcms] Re: help with camera profile

  • From: Ben Goren <ben@xxxxxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Wed, 25 Jul 2012 06:25:03 -0700

On 2012-07-24, at 8:24 PM, Graeme Gill wrote:

>> only digital cameras, but scanning negatives as well. For negatives I obtain 
>> an L* -> L* table
>> by measuring the densities on the film shot of the Kodak N2 target, and the 
>> reference L* values
>> of the target are also known (and measured). The profile composed by refine 
>> is correct if used
>> as a stand-alone.
> Hmm. Note that calibration in the above context is a device space table (ie.
> it is to linearise the device values before mapping them to CIE using
> a matrix or cLUT).

For my own work, I've had to create a DNG profile (though it looks like I'll be 
switching to RAW Developer) with a hand-drawn tone curve that results in output 
where a photo of something has the same L* value as the spectrophotometer 

Would I be better off coming up with a suitable CAL table instead?

If the results would at least be comparable, I think it'd at least streamline 
my workflow -- especially if there were a ``scancal.''

Actually, I'm imagining that that might best be served as an extension to 
scanin. At the very least, most camera profiling targets already include some 
sort of a series of (hypothetically) neutral patches; couldn't scanin use those 
to figure out the CAL table? Might it also be able to make some educated 
guesses about individual channel calibration as well?

I'd be more than happy to help if I can, such as by shooting targets in my 
studio and sending you the resulting TIFFs.



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