> > I think the difficulty is how to decide where the mid-grey point is.
> > Once decided upon then action is easy.
> I thought the tutorial might have had the answer to that by using the
> 50% gray layer with Mode: Difference.
> "This simple tutorial solves this problem by finding neutral gray in
> the image, thereby removing the need to guess the color. In order for
> this trick to work however, your image MUST contain 50% gray tone
> somewhere in the image; otherwise the color correction will be off.
> The ‘Difference’ mode is a comparative layer mode that will invert
> pixels containing 50% gray, turning those pixels black."
> I know there are many ways to achieve the end result, but part of
> these tutorials is about learning and experimenting, so the knowledge
> can be passed on. :-)
I agree with you 100% and an important part of that learning is being
able to discuss the various points raised. It does look as though that
tutorial should help in finding a 50% grey area but, if there is a
colour cast, then that area will never be a pure black and, of course,
the grey area will not be a pure grey.
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