Re: scanner profiling (again)
Re: scanner profiling (again)
- Subject: Re: scanner profiling (again)
- From: email@hidden
- Date: Thu, 18 Dec 2003 10:47:07 -0500
>
So, building on what you said, Tim, would there be any merit with maybe
>
replacing the white patch on your target with something reflective? A
>
small mirror or pen light, for example, would make it possible to
>
establish the brightest white that the camera could capture, wouldn't it?
Adding an emitter may help us to determine the dynamic range of the camera
if we compare it so some deep shadows in the same frame, but even emitters
vary greatly in brightness and color temperature, so we can't use one
emitter to somehow measure our camera's absolute white point.
Reproducing the natural color of the white point in the image, as captured,
is key to "setting" our eyes, if you will, to the rest of the color in the
image, since we use the white point as a kind of reference key for all the
other colors we experience in an image. Adding any arbitrary reflectors, or
worse, a pen light of undetermined color temperature will not bring us
closer to the goal of knowing the "correct" white point we need to create an
accurate profile of a given situation (unless that pen light is the subject
of the photograph).
Having said all that, a photographer friend of mine responded off list,
saying, in order to use a target, shot with a camera, to create a profile,
the white patch in the target should be profiled so it has a lab value =
192,0,0 (instead of an absolute wp value of 200,0,0). This idea made good
sense to me when he said it since it gives you 8 steps of head room for
emitters and such.
Tim Lennox
retoucher and pre-press specialist
E & B Giftware, LLC.
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