One of my frequent subjects is landscapes with dramatic clouds. Sometimes, I take one exposure for trees etc and then a darker one for the sky. Then I use levels to enhance the sky-drama. My problem is the transition from the edge of the foliage into the sky. Once the blue areas of the sky are darkened, foliage shows an abnormally pale fringe instead of transitioning normally into the darker area. (This boundary area is about 3 to 6 pixels.) A tutorial I found isn’t helping, because it recommended Threshold, which arbitrarily chops the boundary, and a different type of ugliness resulted. I can’t be the only one to have tried this?
It sounds like your images are slightly misaligned, which is going to be difficult to solve with the GIMP.
There are several tools that could help you out before you get to GIMP.
- Hugin’s align_image_stack (probably the easiest)
- Hugin GUI to aiign and fuse the image using enfuse
- LuminanceHDR or HDR Merge or Darktable or Hugin to create an HDR file
I also do this kind of sky blending from time to time. There are two articles here on pixls.us that deal with exposure blending with sky transitions:
and
Also, if you have an example that you can share I’d be glad to give it a try and post back my result and steps, if you like.
You’re seeing the ugly transition due to your foliage image having light skies, while your adjusted skies image are darker. Masking the two can be tricky, but there are a few different ways to approach the problem (as @Carmelo_DrRaw already noted and linked). There is also the use of Luminosity Masks to help automatically create a self-feathering mask based on tones, but watch out near areas of similar luminosity.
Do you have some small sample of the two images you could link for us to see? I might have time for a quick video at lunch…
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Thanks all for responding. Alignment was done down to the pixel by varying opacity on the top layer to make sure one thing was directly above another.
The solutions applicable to what’s going on with me are probably in the Carmelo_DrRaw and patdavid links. I’m checking that out now!
I’m about an hour into the tutorial on Luminance Masks (using the Saul Goode script). I wish I had learned this several years ago!! Now I understand what was meant by “self-feathering.” That may not be scientifically accurate, but it beautifully describes the visual results!
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They really are a first step into a new way of looking at your processing approaches. Have you tried the aggressive curve coupled with the “mid-tone” masks? Interesting local contrast + color pop…
I have an image of roiling gray clouds before a storm, so creating contrast and interest in the mid-tones is my goal right now. So much easier with luminosity masks.
That looks already very well done! I cannot see any visible halo transition between the trees and the clouds, and it globally just looks natural to me.
A possibly useful tip: when checking your image for possible halos, scale it down until it occupies less than 1/4 of your screen. From my experience, our brain detects abnormal tonal variations much more easily if it is not distracted by small-scale details.
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Looks clean! You can also try the “Freaky Details” filter in G’MIC if you’re looking to enhance the mid tone details.
Which one, can you link?
Here’s the one I’m using …
https://www.gimp.org/tutorials/Luminosity_Masks/
and here’s one with some technical info I plan to read later …
http://blog.patdavid.net/2011/10/getting-around-in-gimp-luminosity-masks.html
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