0 Replies Latest reply on Apr 22, 2015 9:44 AM by Linwood Ferguson

    What is the best sequence for tone corrections on inverted negatives?

    Linwood Ferguson Level 1

      I am photographing old slides and negatives, getting good images, but...


      I really like using Lightroom, for space reasons if nothing else, however I am struggling to get good color correction in these.


      I know how to invert the tone curve, this is not a basic "where do I start" question.  I've done hundreds (maybe thousands) and experimented a lot.


      First, I can get pretty good results in custom products.  Vuescan for example works pretty well on most negatives, and is a good test for "has age ruined it or is it my poor edits".  And I COULD output positives as JPG and store them beside the raw images (of course Lightroom in this case is backwards in that what I would want to "see" is the JPG, but that's OK, I can stack or something).


      Secondly I can get better results in Photoshop, especially since the tone curve inversion is destructive (i.e. it really becomes a positive instead of just looking like one), so subsequent editing tools work as expected (e.g. droppers).


      But Lightroom is very frustrating in that it is ALMOST usable.  If I just work randomly with the controls I can often reach a good result, but the result tends not to be applicable later -- follow the same sequence and/or actual settings and I get garbage on a different roll.


      My question is whether anyone has a good algorithm for how to approach the problem?


      For example, I've tried this:


      - Crop to just a tiny portion between frames (which should end up being black)

      - Adjust color temp to make it white (which will become black)

      - Adjust (various: exposure, highlights, etc.) to move it nearer 100%

      - Invert tone curve

      - Find a mostly neutral color and crop to it (I'm cropping so I can see the histogram only of it)

      - Adjust the R, G, or B tone curve to make it white

      - Add contrast by making the inverted tone curve RGB into a slight "S"


      The result is something that looks like it was made in 1905, weird color casts, poor contrast, whites are yellow/grey.  Then fiddle -- fiddle for a long time.  Some get very good, some poor.


      But the "fiddle" doesn't seem very targetted.  All the postings say "controlls are reversed" but that's misleading -- exposure is reversed, but most of the others are more confused than that, with (for example) the white/black/highlight/shadows all affecting color cast strongly in addition to their respective name.


      It strikes me that there should be a fairly deterministic approach to this, if one understands exactly what happens with each control (I do not pretend to).   For example - maybe I should invert first, and try to find neutral rather than the black (white pre).  Maybe I should be using the HSL sliders to take the tone out post invert instead of the R, G, B tone curves.  Maybe I should be using the R, G, B curves by displacing them but leaving at a 45 degree angle, or maybe I should use it as a curve centered on the color cast of the negative. 


      Maybe I should be building a camera profile instead of using the develop tools.


      I hesitated to post this yet-another-how-to-invert posting, but I hope that someone has dug deeper into this and has a more algorithmic approach than I have.