[argyllcms] Re: Calculating film LUTs for a film recorder

  • From: Philip Pemberton <philpem@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Mon, 27 Aug 2012 20:04:58 +0100

On 21/08/12 02:16, Graeme Gill wrote:
>> I've actually got a Spyder2Print calibrator, though as I understand it
>> that isn't supported by Argyll :(
> Sorry, it's a lot of work to RE something like that, since it's
> quite different to other spectrometers.

Yeah - I've been trying to reverse-engineer it off-and-on for a while.
I'm not really getting anywhere, unfortunately.

>> It's a linearisation LUT. From what I can tell, it's intended to counter
>> the effects of the film's characteristic curve (H-D, or
>> "Hurter-Driffield" curve). Although as you say, matching to sRGB may be
>> easier and more productive.
> printcal wouldn't be too hard to modify to target a particular curve shape.

Well based on what I've reverse engineered from the film profiles, I
need to set the luminance of the CRT (this is different for each film)
then build a LUT to linearise the response. I suspect the luminance is
set to allow the film to be exposed in a reasonable time while also
providing a usable dynamic range and avoiding issues with reciprocity
failure in the film.

This project is getting more difficult by the minute :-/


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