U of S | Mailing List Archive | alt-photo-process-l | Re: curves and gum and Christopher James book

Re: curves and gum and Christopher James book

Hi Henry,

Sorry about the delay in replying. I'm down-under at the moment so your sleep is my awake.

My work-flow when applying this curve is as follows:-

open image and adjust to taste in RGB colourspace

Split the channels

Select first channel to work with

convert to RGB

'apply image' with layer set to multiply 

apply adjustment curve

invert to negative


This results in a negative with much less contrast generally when compared to the same image with the curve applied to the negative. This is what works for me for SOME images. 

I hope this helps 




On Mar 10 2008, Henry Rattle wrote:

Thanks, everyone, for the reviews of the new book. I'll be ordering one when
it hits the UK on April 1st.

Meanwhile, something puzzles me.

Someone mentioned David Hatton's gum curve being in the book, sourced from
the Alternativephotography website. Out of curiosity I looked it up there,
and it looks pretty similar to my own gum curves (though along with
Christina I find that different colours give different curves, especially

However one thing puzzles me - there's a note alongside the curve which says
"Note from David: The curve is applied before inversion to a negative and
the image should be RGB."

Now my practice is to apply my curves to the negatives, after splitting the
RGB channels and inverting, and before colorisation - following Mark
Nelson's PDN.

But shouldn't the curve you apply to a positive before inversion be the
inverse of a curve you apply to a negative after inversion?

Or do I understand this even less than I thought I did? David? Anyone?