Re: X-Rite Passport Inaccuracies
Re: X-Rite Passport Inaccuracies
- Subject: Re: X-Rite Passport Inaccuracies
- From: Justin Krug <email@hidden>
- Date: Fri, 20 Sep 2013 12:43:17 -0700
- Importance: Normal
I had sent this to Tom without CC'ing the list.....not sure what the protocol is in this case, but I thought I'd send it along in case someone else wanted to chime in as well. Thank you for all the input thus far.
Tom
Thank you very much for the detailed response. If I'm not mistaken there are two issues at play.
1)
First, there is the problem of matching color across different light
sources (including 100% CFL's), for which I understand you to say that's
outside of the capabilities of the Passport and other DNG profiles.
I'm better off using the HSL sliders to get the color right there. To
do that I would probably set some color sampler points on swatches and
get the RGB values close between different shots of a color checker
under each light source. However, it seems like Lab would be a better
color space, so I could look at color only, and that's not available in
Lightroom. Otherwise I'm not sure of a reliable way to do that.
2)
Then there is my test, which I first conducted in daylight (overcast)
with the 60d and 5d. In that case the Passport proved to be no better
than the Adobe Standard Profile in correcting colors or matching colors
between cameras. Am I mistaken in thinking this is basically the test
you were suggesting I do? Or is there something special about warm
daylight?
Here is the data from my test--
The color values after correction with the Passport (given in a,b values of Lab):
5d: green= -51,39 red= 69,41 yellow= 4,86 blue= 27,-65
60d: green=-42,34 red= 60,39 yellow = 4,79 blue= 25,-53
The color values prior to correction with the Passport, using Adobe Std (given in a,b values of Lab):
5d: green= -47,36 red= 61,37 yellow= 1,87 blue= 18,-59
60d: green= -38,31 red= 56,33 yellow= 2,78 blue= 16,-46
I cannot discern any appreciable change in the difference between the color values of the 5d and 60d using the Passport.
Thanks,
Justin Krug
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