Re: Primer on photographic exposure, etc.
Re: Primer on photographic exposure, etc.
- Subject: Re: Primer on photographic exposure, etc.
- From: Lars Borg <email@hidden>
- Date: Wed, 15 May 2013 12:19:48 -1000
Still, with such a target you're calibrating only for reflective colors.
Shouldn't you include more colors near the spectrum locus?
Don't you get a lot of on-spectrum-locus colors ending up outside the
spectrum locus?
(A common problem with camera calibration)
On a separate issue:
Sure there are target tolerances for the same SKU.
(And camera tolerances for any given camera model)
Do you have actual dE numbers?
Are these tolerances bigger than the color inaccuracy of the camera
system itself (which is maybe 10 dE over a large set of colors after
calibration)?
I'm curious, as AMPAS has similar issues with camera calibration.
BTW, any experience with the Image Engineering camSPECS?
Lars B
At 11:05 AM -0700 5/15/13, Iliah Borg wrote:
Dear Ben,
I'm just saying that C1 prefers LUT profiles, and there are 2 ways
of doing it - make a matrix and convert to LUT; or make LUT
directly. One can do both and keep both, they both have their own
advantages.
For a minimal profile 24 patches is too little with current
profiling engines, matrix or LUT, does not matter. ColorCheckerSG
with its 140 patches is a far better choice. Making a combined
target from 3 shots of SG bracketing the exposure by 2 stops is even
better. Target needs to be individually and accurately measured,
canned measurements do not fit well. Scaling for a combined
420-patch (140*3) target is easier if measurements are spectral.
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