Re: curves and gum and Christopher James book

[Ender100@aol.com]

An easy way to compare a curve applied to a positive vs a curve applied to a negative is to do the following:

1.   Take a 21 step digital step tablet

2.   Apply your curve to the step tablet

3.   Flatten the layers

4.   Use Image>Adjustments>Invert

5.   Read the values of the steps with the eyedropper tool

6.   Create a curve with points that have the output values set to the values you read for each step

Hope this helps!

Mark Nelson
Precision Digital Negatives
PDNPrint : Precision Digital Negatives
Mark I. Nelson Photography


In a message dated 3/10/08 8:51:30 PM, cryberg@comcast.net writes:


> Folks:  Several of you have responed to Henry's question with suggestions of
> what he might do--but that was not his question.  He wants to know--and I do
> too--how one person's curve for a positive can look much like another's
> curve for a negative.  One answer seems to respond to his question, but I
> don't understand it--here it is:
>
> You have to REALLY pay attention to the curve mode being used to display the
> curve. A curve calculated for graphic mode (applied to a positive) will, on
> the surface, look exactly the same as a curve applied to a negative -- BUT
> since PDN users generally work in binary mode it is this change of mode
> which functions to invert the curve.
>
> What is a curve calculated for graphic mode?  Why will it look exactly the
> same a a curve applied to a negative.  What is binary mode as opposed to
> graphic mode?










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