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I took this photo at night:

enter image description here

there is a green bush between the two chairs at the right, and green synthetic grass below the chairs, but they are barely visible.

Is there any way to improve this picture in GIMP such that it looks more lively (e.g. with the appropriate parts green)?

  • 3
    There simply isn't enough information in this photo to bring out any detail without introducing an enormous amount of noise. The best way to fix this photo without changing the feel is to put the camera on a tripod and retake it with a long exposure. Low light sensitivity, narrow aperture, and long exposure means you get more light (meaning more colour detail) with less noise. Something like ISO100, F9, and a 10-second aperture should be a good place to start—tweak the exposure and aperture till you get a result you like. – Janus Bahs Jacquet Jun 10 '17 at 16:35
  • You could apply a levels or curves adustment in GIMP, but as @Janus Bahs Jacquet says - all you get is quite a noisy image, and there is little to no colour information in the image anyway. A photograph like this requires a long exposure (and a camera on a tripod), or the use of artificial lighting. – Billy Kerr Jun 10 '17 at 17:10
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With ImageMagick,

magick chairs.jpg -resize 25% -gamma 4,6,4 chairs_464.jpg

Produced this

image

which is not as green as you'd probably like (there's really not much of a green component to amplify), but at least you can make out the scene a little better.

The command applies gamma separately to each channel (gamma_red=4, gamma_green=6, gamma_blue=4) to brighten them; here I was attempting to brighten the green channel more than the others.

ImageMagick has an "-auto-gamma" option that seems to be just as effective in handling underexposed photos. Here's the result of

magick chairs.jpg -resize 25% -auto-gamma chairs_autogamma.jpg

autogamma image

which uses the mean values of each color channel to come up with the equivalent of

-gamma 4.616,4.649,4.680

Note that in earlier versions of ImageMagick, the command is "convert" instead of "magick".

With GIMP you can do more-or-less the same thing via the "colors/curves" menu item and lifting the middle of the curve to approximate a gamma curve.

EDIT: I've just become aware of Fred Weinhaus' "autotone" script, available from his website, for noncommercial use only. It does a pretty nice job on this image, when run with the default options:

  • Thanks! This does not contain green, but at least it is possible to see that there is grass and a bush. – Erel Segal-Halevi Sep 17 '16 at 21:50
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Green from things like grass doesn't really exist at night. There is not enough white light to reflect off the grass to create a green perception. You can confirm this with an eye drop of your image, even on the brightest part of the grass its leaning towards Magenta instead of Green.

So, can you fix this? It would require extensive masking and painting in exactly what you want and where otherwise you'll just have a big green color cast. The best way to fix this would be to take the photograph during the daytime.

  • Or use a flash, or another light source to lighten up the scene. I guess a softbox if out of the question. – Alin Sep 16 '16 at 15:16

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