How To Manage Trees In Your AstroImages Using GIMP

How To Manage Trees In Your AstroPhotographs Using GIMP

Sometimes your pictures of the night sky contain foreground elements, like trees. These can really add to an image's composition. Unfortunately, many of our astroimages also contain light pollution which can ruin a good picture.

In a previous post I demonstrated how to remove light pollution using GIMP. The problem with this technique is that it left foreground elements like trees looking terrible. The video on this post shows you how to make the trees look good after the light pollution has been removed. It uses a layer mask technique. This creates a picture of just the tree on a transparent (or almost transparent) background. So you can paste your tree onto any picture you want. 

The trick to make the final image look good is to make your tree on a transparent background image first. Then use the clone tool to paint night sky over the tree in the original image (As shown in the how to remove light pollution using GIMP video) Use this image as the new original and create a light pollution removing image from this as shown in the previous video on removing light pollution. 

You should now have three images to make the final picture. You start with the new original image (the one with stars showing and the tree removed), then layer the tree transparency on top of this, then layer the light pollution removing image on the top and subtract it. The result will be a picture with no light pollution and a much better quality image of the foreground tree.

Have fun. It can be a bit tricky to get right but it's worth a try.

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