[argyllcms] Re: colprof viewing condition overrides
- From: Greg Mikol <gmikol@xxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Tue, 15 Mar 2011 15:25:06 -0700 (PDT)
Reposting this with a subject line so it gets threaded correctly.
Graeme Gill wrote:
> Greg Mikol wrote:
> > I'm having trouble understanding the difference
> > between adaptation luminance and surround
> > luminance, as well as between the surround and
> > the background. Also, how having prints be not
> > matted, matted with white, or matted with a
> > darker gray or black might affect these values.
>
> Have a look at page 49 of <http://www.argyllcms.com
> /FCMS2010_ArgyllTute.pdf> and see if it helps.
>
>Graeme Gill.
Helps a little bit...but I'm still trying to nail down the details. Here's what
I've worked out so far:
The illuminance on the hanging wall is 550 lux, so if I follow everything:
Li = 175 (550 lux / PI)
The entirety of the hanging wall is illuminated by the lights (not narrowly
focused on just the prints), and it's reflectance is ~50%., so La=87.5 (175 *
0.5).
Yb=20% (assuming average scenes).
Media white point is XYZ = 84,88,76 so
Lv= 175 * 0.88 = 154
La/Lv is 87.5/154 = 56.8%, so surround=average.
Am I correct in understanding that if the spotlights were more narrowly focused
on just the prints, then La would be lower?
Have I got this right?
--Greg
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