[argyllcms] Re: Number of patches - well behaved printer?

  • From: Rishi Sanyal <rishi.j.sanyal@xxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Wed, 23 Feb 2011 16:51:41 -0800

"Profiling from a composite target allows to reach both Dmin and Dmax;
but tone curve still needs to be addressed elsewhere as usual."

But when you're building a profile from a Velvia IT8 target, say,
you're really trying to measure the tone response curve of your
scanner, not of the film, right? I thought that after recording the
IT8 chart on the film, Wolf Faust measures the spectral data of the
patches on the film using a standard illuminant, then stores these XYZ
values in a measurement file that the profiling software then uses to
map the scanned values to the spectral values. This means that the
scanner is trying to recreate the colors on the film, not the colors
of the original chart (which I would imagine could get messy depending
on the tone response of the film itself).

Am I understanding something incorrectly here?

Thanks,
Rishi

On Wed, Feb 23, 2011 at 4:38 PM, Graeme Gill <graeme@xxxxxxxxxxxxx> wrote:
> Rishi Sanyal wrote:
>
>> You mean to get color accuracy for the transfer onto the final
>> transparency that gets sent to theaters (kind of like the reverse of
>> profiling a scanner+film combo)? Hollywood shoots negative for its
>> latitude... I thought it was interneg all the way until the final
>> print, which I'd assume is on transparency (transferred by a film
>> recorder).
>
> I don't recall all the details, but it was something like creating
> a lookup to map from density to CIE/spectral values for converting
> to/from something like Cineon format, which is based on density.
> It may have been positive or negative film or both.
>
> Graeme Gill.
>
>

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