Episode 163: Colour Curves

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Years ago I bought a used Peleng Fisheye and never used it much. So I took it for a walk and shot some scenes here in Berlin. At the top is an image of the famous TV tower at the Alexanderplatz.

After a bit of ramblings about Fisheye lenses I process a shot from a hall in the subway station below the Alexanderplatz. There I use the curve tool to get the colours “right”. Not “right” as in “true to reality” but as in “the right atmosphere”. Tweaking the red, green and blue colour channels can change an image quite a lot.

Never stack curve operations – do it in one step. A little experiment shows the result of not following that advice. A nice recall feature in the curves dialog allows it to reload the last curves. In case of an error just Undo and tweak your curve.

I am absolutely not sure how to sharpen the image. Help me in the forum!


00:30 Peleng Fisheye Lens
05:00 Image loaded in GIMP
05:10 Rotating and cropping
06:15 GIMP 2.7.3 remebers the window settings!
06:30 Rotate tool in corrective mode
07:42 Inside out crop
09:20 Copy the layer for backup
09:30 Contrast correction with the curves tool
10:20 A click to early
10:30 Curve operations are stored – easily redone
10:50 RGB colour channels
11:00 Reducing a red colour cast
12:00 Undo changes – not with “Reset”
12:20 Change blue and green in the shadows
14:00 Experiment: One curve operation vs. a series of
16:00 Sharpening the image
17:00 Saving the image
17:30 The Meet the GIMP Forum
18:50 The End

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Meet the GIMP Video Podcast by Rolf Steinort and Philippe Demartin is licensed under a Creative Commons Attribution-Share Alike 3.0 Germany License.
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9 thoughts on “Episode 163: Colour Curves

  1. A show dedicated to a fish-eye, great! I suppose a fully manual lens constrains to very conscious shooting. Unfortunately I’m too impulsive for this so I chose an automatic one, but it’s my absolute favourite lens. Great for landscapes and spheric panoramas. And when I’m fed up with curved lines I’m surprised how good Hugin is in de-fishing … So as a fish-eye enthusiast I say thank you for the show!
    I tried to sharpen the image in different ways but I always failed. Unfortunately I only strengthened the noise instead of optimising the sharpness. No easy challenge for this image …

  2. @Bert
    True, this fisheye is very good. And it certainly helps that Rolf choose nice and impressive places…
    Sharpening this image is interesting. I think it would be easier with the raw and some wavelet magic, both denoise and sharpen/texture increase. Let’s see if Rolf continues on this one.

  3. @Steve
    Would you put this list into the wiki? Installing plugins and scripts is already described there.

  4. @nachbarnebenan

    I would be happy to, but I am not sure how? I would need access to this. I would appreciate a link back to the posterous site if possible.


  5. @nachbarnebenan,

    I think it would make for a useful meetthegimp blog post item — to some of the new users to GIMP who may be unfamiliar with some of these amazing extensions / scripts etc…

  6. Pingback: Episode 196: ENIAC and Me | Meet the GIMP!

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