RE: Humans (and cameras and scanners) do not have a color gamut (?)
RE: Humans (and cameras and scanners) do not have a color gamut (?)
- Subject: RE: Humans (and cameras and scanners) do not have a color gamut (?)
- From: Roger Breton via colorsync-users <email@hidden>
- Date: Wed, 8 Jan 2020 16:50:33 -0500
The "Jack Holm" from HP?
/ Roger
-----Original Message-----
From: colorsync-users
<colorsync-users-bounces+graxx=email@hidden> On Behalf Of
Iliah Borg via colorsync-users
Sent: Wednesday, January 8, 2020 4:36 PM
To: Wayne Bretl <email@hidden>
Cc: 'Andrew Rodney via colorsync-users' <email@hidden>
Subject: Re: Humans (and cameras and scanners) do not have a color gamut (?)
> See Jack Holm's paper ... where he derives the spectral locus of a
> combination of a sensor's outputs and a subsequent matrix
I've read that paper when it was first published on the web ;) It doesn't
define sensor gamut, or gamut of sensor outputs.
To quote,
"This paper reports on the observed characteristics of the capture color
analysis gamuts resulting from a number of capture devices/media, and scene
analysis color matrices."
The result depends on the matrix. Strongly depends, as the paper itself
demonstrates. That matrix defines the relation between the camera observer
and colorimetric observer.
On Jan 8, 2020, at 4:21 PM, Wayne Bretl via colorsync-users wrote:
> Arrgh - addressing problems - went only to iliah and not the whole
> list as intended
>
> -----Original Message-----
> From: Wayne Bretl <email@hidden>
> Sent: Wednesday, January 08, 2020 2:13 PM
> To: 'Iliah Borg' <email@hidden>
> Subject: RE: Humans (and cameras and scanners) do not have a color
> gamut (?)
>
> See Jack Holm's paper, which I posted above, where he derives the
> spectral locus of a combination of a sensor's outputs and a subsequent
matrix:
> http://www.color.org/documents/CaptureColorAnalysisGamuts.pdf
>
> Although he does not show the sensor outputs themselves, they have
> reached their extreme possible ratios when the stimulus is a single
> wavelength, and therefore a pseudo chromaticity chart could be plotted
> using the ratios of one channel to the sum of the three on one axis
> and a ratio of a second channel to the sum on the orthogonal axis.
> This chart would have a defined gamut of sensor values (inside the
> spectrum locus) but would not represent colors per se until processed
through a matrix.
>
> Holm shows the resulting chromaticities for multiple sensors and
> several reasonable matrices. He includes cases for motion picture
> negative film that clearly show a triangular gamut limit (spectral locus).
>
> -----Original Message-----
> From: Iliah Borg <email@hidden>
> Sent: Wednesday, January 08, 2020 1:59 PM
> To: Wayne Bretl <email@hidden>
> Cc: Andrew Rodney <email@hidden>; Andrew Rodney via
> colorsync-users <email@hidden>
> Subject: Re: Humans (and cameras and scanners) do not have a color
> gamut (?)
>
>
> On Jan 8, 2020, at 3:52 PM, Wayne Bretl via colorsync-users wrote:
>> .
>> The discussion has moved beyond the true but uninformative statement
>> that cameras (sensors to be precise) do not have a color gamut , to
>> considering how the gamut of sensor outputs
>
> I would very much like a definition here. What is the gamut of sensor
> outputs?
>
> And of course, how to measure it?
>
> --
> Best regards,
> Iliah Borg
> LibRaw, LLC
> www.libraw.org
> www.rawdigger.com
> www.fastrawviewer.com
>
>
>
>
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--
Best regards,
Iliah Borg
LibRaw, LLC
www.libraw.org
www.rawdigger.com
www.fastrawviewer.com
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