How can I avoid blurry tree branches when merging bracketed HDR shots?
Asked 8/11/2018
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I’m new to HDR bracketing and am merging three exposures in Aurora HDR on macOS. With scenes that include fine tree branches, the merged result looks blurry/ghosted even though a single exposure looks sharp. Is this mainly caused by misalignment, subject movement, or my shooting settings? What can I do when shooting and merging bracketed HDR images to keep branches as clear as possible?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
7y ago
2 Answers
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There are usually small variations between images when you shoot a stack for HDR, especially shooting handheld. Wind may cause larger variations, as well as other moving entities within a shot (such as a pedestrian in the distance).
Photo editing software is good at dealing with these variations. However, certain items, especially complex/movement-prone ones like tree branches, may require manual intervention to avoid "ghosting".
Shooting
We want to give the software the best source material we can.
- Shoot on a tripod; if handheld, be sure that your shutter speed is fast enough that your movement won't cause blur, even on the longest exposure.
- Avoid long delays between exposures (shoot the stack as fast as possible).
- Shoot plenty of images for the stack, but try combining only some of them for the best result. The more images, the more variations the software must deal with.
- Try to use settings which give at least one decent exposure at a fast enough shutter speed to eliminate the movements you can't control (like wind). Other images in the stack may have movement.
Deghosting
"Ghosts" are removed by deghosting.
I don't use Aurora often, but this tutorial discusses the deghosting process in Aurora and the results look good: https://youtu.be/7OuIfowv8U8
Lightroom supports automatic deghosting. Photomatix (my preferred tool, and similar to Aurora) supports deghosting and does a fantastic job of it when starting from good source material.
You can also manually recreate and/or tweak the repair using a tool like Photoshop.
- Find an image which is clear.
- Copy the portion of the clear image over any blurry portions of the composite.
- Adjust the copied "piece" so that it blends with the composite image.
Examples
This image was shot during heavy wind and rain. The tree above the truck showed movement, so I selected it for deghosting in Photomatix.
The flag in this image showed movement. I recall manually editing this image using the aforementioned technique to blend a sharp version of the flag into the composite image.
Originally by user20122. Source · Licensed CC BY-SA 4.0
user20122
7y ago
0
Generated from our catalog & community — verify before relying on it.
Blurry branches in HDR merges are usually caused by movement between frames, not just software alignment. Fine branches are especially prone to ghosting if you shoot handheld or if there’s any breeze.
To improve results:
- Use a tripod whenever possible.
- Keep the bracket sequence as fast as possible to minimize changes between exposures.
- Use a fast enough shutter speed, especially for the longest exposure, if shooting handheld.
- Keep the aperture the same for every frame; vary shutter speed for the bracket. Changing aperture changes depth of field and can make the merge look soft. Aperture Priority is an easy way to keep f-stop fixed.
- Be cautious with moving subjects: even slight wind can shift branches enough to blur in the final HDR.
Software can often handle small alignment differences, but complex moving details like leaves and branches may still need de-ghosting or manual correction. In some conditions, the limitation is the scene itself: if the branches are moving, perfect HDR merging may not be possible. Waiting for calmer conditions, using fewer frames, or avoiding HDR for that scene can give a cleaner result.
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