Gimp-Forum.net

Full Version: Resurrecting old color slides
You're currently viewing a stripped down version of our content. View the full version with proper formatting.
I have a large pile of color slides, most taken 45-50 years ago, on either Ektachrome or Fujichrome.

although they've been stored in boxes that keep them in the dark, the colors of many have faded, the amount seems rather variable. (there is also a good bit of dust/dirt, that I'm not going to mess with unless I can also improve the image's colors to something closer to original.)

I'm looking for ways t try to return at least some of the vitality they had when new, but am sufficiently ignorant of complex photo processing that I haven't a clue where to start.

I've tried messing with curves, contrast, hue/ etc but can't get anything I like the looks of.

Can any of you suggest things I could (learn to) do to retain at least some of the original verve?

I'm attaching an example of one of the slides.

Fredex
If you look at the histogram (the shape in background of Curves), your photo has no highlight (the histogram should touch the right side). And if you take out the Pointer dialog and explore the clouds, you find that the green component in them is a bit weak (they should be neutral gray). So a quick fix is to use Curves on each channel to:

  1. restore the white point by making the curve hit the ceiling where the histogram stops
  2. increase contrast a bit by giving a slight S shape to the curve
  3. give a small boost to the Green channel by putting its curve slightly above the two others.
[attachment=4601]

[attachment=4602]

Remarks: to minimize color loss:
  • Work in 32-bit precision
  • It's best of you do everything in one shot (which is why Curves is the best tool)
Otherwise, did you try Color>Auto>Equalize?
(06-29-2020, 09:49 PM)Ofnuts Wrote: [ -> ]If you look at the histogram (the shape in background of Curves), your photo has no highlight (the histogram should touch the right side). And if you take out the Pointer dialog and explore the clouds, you find that the green component in them is a bit weak (they should be neutral gray). So a quick fix is to use Curves on each channel to:

  1. restore the white point by making the curve hit the ceiling where the histogram stops
  2. increase contrast a bit by giving a slight S shape to the curve
  3. give a small boost to the Green channel by putting its curve slightly above the two others.




Remarks: to minimize color loss:
  • Work in 32-bit precision
  • It's best of you do everything in one shot (which is why Curves is the best tool)
Otherwise, did you try Color>Auto>Equalize?
Ah, thanks for the pointers! I know just enough about photo editing to be able to cut and paste, or run unsharp mask, so your advice will probably be a huge help. I could see that green was missing but didn't know the proper way to augment green without screwing up other colors. I'll give it a whirl over the next few days (if I can--we are trying to do huge downsizing so we can move this summer, so free time to play with photos is at a premium) and see what happens.

Thanks again!

Fred
Ofnuts:

I tried using curves as you suggested, but I apparently have a  manual dexterity problem... doing as I think you wanted me to do is something I don't seem to be able to do, as it requires tiny precise motions of the mouse pointer, which I apparently can't do.

so I dropped back, punted with the levels dialog where I'm able to do something similar (if not the same) to what you suggested and I'm getting pretty good results:

-drag the right-most pointer back to where the histogram goes to zero,
-open the green channel and drag the right pointer back some small amount til the purple disappears or fades, but not so far as to start turning light/white-ish things into faint green things.

-Add in some unsharp mask hacking and occasional other minor tweaks and I have some fairly decent looking images.

[attachment=4616]
[attachment=4617]

(this is a shot of Lake Powell, behind the Glen Canyon Dam in Arizona, circa Aug 1973, taken from the bridge over the canyon just downstream from the dam, early morning sun, facing northward. Asahi Pentax Spotmatic, probably my 200mm fixed-length lens.)
It all depends on the image. The first one lacking in green, as seen from the foliage.

I though a straight Colours -> Auto -> White Balance gave a reasonable result. https://i.imgur.com/9NQfMVv.jpg Add more green with colour curves as required.

The second one, not the same subject by all means. Again a Auto white balance gives a result https://i.imgur.com/Pcmgykp.jpg If you have a shaky hand then consider the gmic plugin http://www.gmic.eu Lots of filters / options, auto and manual but using sliders that are a bit easier to manipulate. https://i.imgur.com/8iRHHUf.jpg

If it is any consolation, I have (unfortunately not so many, lost a few.) similar. Taken in countries where photography was frowned on Wink camera sat in hot LandRover, film, often months before processed, colours degraded. A lot is all about the memories they evoke, not necessarily the quality.
(07-04-2020, 03:01 PM)fredex Wrote: [ -> ]Ofnuts:

I tried using curves as you suggested, but I apparently have a  manual dexterity problem... doing as I think you wanted me to do is something I don't seem to be able to do, as it requires tiny precise motions of the mouse pointer, which I apparently can't do.

Several things:

  1. If you enlarge the window in either direction the mouse movements are proportionally scaled down
  2. Once you have clicked on the curve to create a point, you can move the point up/down usi,g the cursor up/down keys
  3. Since 2.10.12 , there are input/output spinners at the bottom left that let you enter values by hand.