Re: curves and gum and Christopher James book
A correction curve that is meant to be used on a positive image before inverting to a negative should not be confused with a curve that has to be applied to an allready inverted image. There are two 'schools' of curving for digital negatives. It's a bit like driving left or ride side of the road. In both cases you will arrive from A to B but you should never mix the methods.
Anyway, sometimes it comes handy to change a 'before inverting' curve into an 'after inverting' curve. For example when you want to build your curve into a QuadTone Rip profile.
This can be done with the Curve Merging technique described here: http://polychrome.nl/weblog/curve-merging
Actually you will not merge two curves here but you 'wrap' a curve layer with your curve loaded between two invert layers. Then you have to flatten this package and save the .raw file as a .amp curve. When you load that curve you can change it to a regular .acv by clicking on the pencil symbol in the curves palette. When I find some time this week I'll write an article about this on my site.
On 10 mrt 2008, at 20:09, Henry Rattle wrote:
Michael – you are right, of course. But my question was more about – shouldn’t a curve that you apply to a positive, curve in the opposite direction from one you apply to a negative?