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This is based on using CaptureOne software and the
measurements taken in the small sample windows on the Gray Balance screen. For
this testing the gray balance setting is set to "As Shot" and no gray balancing
has been performed in C1. The image is a RAW capture of a Gretag ColorChecker
taken with a P25 digital back. The destination profile is set to Adobe
98.
If the "current" values (the values shown in the
Current window, i.e. the raw RGB values before processing through the CMS) of
patch 7 read 221,120,50 (R,G,B) and the the No Color Correction camera profile
is selected as the camera source profile, the Adobe 98 destination values read
216,142,176.
If I do nothing else but change the camera profile
to P30 Product Flash for example, the Adobe 98 values change to 227,121,51,
which is a considerable difference from the NCC profile. Selecting another
camera profile, such as H101 Generic results in still a different set of Adobe
98 RGB values, 213,144,62. (btw, these camera profiles were just chosen
arbitrarilly to see how the RGB numbers are affected with various
profiles)
So this tells me that the camera back models see
color considerably different from each other, which makes sense. I would assume
that if the image I was viewing on screen was actually shot with a P30 in a
product type shooting environment and the P30 Product Flash profile was
selected, the Adobe 98 RGB values reported by C1 would closely match those of a
shot from an H101 with the H101 Generic profile selected. Does that make
sense?
So if I follow the same logic, gray patch #21
should also produce different Adobe 98 RGB values if I select different camera
profiles, just as in the example above for patch 7. However this is not the case
with C1. Using the same camera profiles as above while measuring patch 21 I get
these results:
camera profile = "" color Corection
Current =
169,170,170 --> Adobe 98 = 182,183,183
camera profile = "" Product Flash
Current =
169,170,170 --> Adobe 98 = 182,183,183
camera profile = "" Generic
Current =
169,170,170 --> Adobe 98 = 182,183,183
So it appears that regardless of the camera profile
in use, the gray patch values remain constant. Not only that, they are as if no
camera profile is even being applied since the NCC profile produces the same
results as the other profiles.
In my thinking, the only way this could happen is
if each camera back sees the gray patches exactly the same. Is this possible? I
don't think different camera backs would see colored patches differently but
then see neutral patches identically across different models.
So based on that let's assume that the scene I'm
shooting consists of just a grayscale. Based on what I'm seeing, it wouldn't
matter what camera profile was selected, even if I selected the NCC profile, I
would get the same results once I took the shot and converted it to Adobe 98
color space. How can it be that no matter what profile is assigned as the camera
profile in this scenario (even profiles from other manufacturers produce the
same results), the resulting Adobe 98 RGB values are identical?
I've posed this question to PhaseOne but they have
not given a reasonable answer so I'm posting here. I don't think they understand
exactly what I'm asking. Hopefully this make sense. Am I just completely
missing something?
Thanks
Chris
McFarling
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