Re: Real-world RGB numbers for the ColorChecker SG
Re: Real-world RGB numbers for the ColorChecker SG
- Subject: Re: Real-world RGB numbers for the ColorChecker SG
- From: Roger Breton <email@hidden>
- Date: Tue, 21 Jun 2005 17:58:59 -0400
> I believe Mr. Miller is referring to RGB values for the gray patches on
> the ColorChecker SG. When used on some high-end cameras that allow for
> tuning of the tonal reproduction curve (TRC), these values can be used
> to calibrate the exposure conditions for fine art reproduction.
>
> In this instance, the exact chromaticities of the RGB primaries can be
> ignored because the assumption is made that the camera is adjusted to
> produce equal RGB values for a neutral reference. The more important
> point is the gamma value to use for the camera's RGB values. Using the
> green channel RGB value only, adjusting the exposure to achieve a
> particular value for the chart's white patch, then tuning the rest of
> the gray patch values to achieve the reference value, a very consistent
> shooting situation is created that produces a more accurate profile and
> allows the profile to be used in subsequent similar shooting
> conditions.
>
> For more information on this procedure, check the www.betterlight.com
> website in the Downloads/Macintosh area for the Repro Curve package.
> The tables do not yet have values for the ColorChecker SG (they are
> being edited right now), but you can get an idea of the procedure.
>
> Robin Myers
Are there lot's of people who prefer this kind of RGb workflow for digital
capturing the SG? I guess the tools are not very widespread for doing this
in device-independent space. Which tools, Robin, are you implicitly assuming
on the user's part in your description?
Roger Breton | Laval, Canada | email@hidden
http://pages.infinit.net/graxx
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