Ghosting happens in HDR images when something moves. For example, leaves in a tree blow in the wind and are captured in different positions in the different exposures. When those exposures are merged and tonemapped, the ghosting appears.
Ideally, when photographing trees, I want to do so when the wind is still. But that is not always possible, especially when I am out of town. But there are solutions to this problem.
Here are the three images I used on what was a low contrast day. I spaced the exposures one stop apart, auto-bracketed.
There was a soft breeze blowing, so I knew I would have some issues to overcome, as the Spanish moss was swaying back and forth. And as you will see below, I also had some leaves movings, which caused ghosting.
Here is a closeup detail of a section that shows the ghosting:
There are two ways to go about resolving this issue. The first one I want to discuss is using Photomatix Pro 4′s semi-manual Reduce Ghosting Artifacts command. Shortly after you drop your files into Photomatix Pro 4, you will see this menu:
Select that option and hit the Preprocess button on the bottom. You will next be greeted by this menu:
This window gives you the opportunity to select multiple areas of your image that contain ghosting. It’s easy to do, too. The first step, as the directions indicate, is to drag with your cursor, a border around the area you want to select. You can adjust the brightness and size of the image with the sliders on the bottom so that you can see your outline more easily. Here is my initial selection:
Then you must do the second step of Control-clicking or right-clicking inside the area to mark it as ghosted. This is required before you select another area in your image:
Your dotted white line now becomes a solid white line and you can now preview the deghosting:
So here is the result of the deghosting, which you can compare with the image detail I showed you previously which had no deghosting:
There is some improvement, but not enough. So this leaves us with the second approach, which is a full-manual approach. This involves using one of the separate exposures as a layer in Photoshop. In this case, the under-exposed image was my choice because it was just one stop under-exposed. I want this exposure because it uses a quicker shutter speed, with the result that the leaves and Spanish moss are less blurred.
Before I loaded this under-exposed image as a layer, I made some adjustments in Photoshop so that the luminance levels of the leaves were approximately the same as the HDR image. After I loaded the image as a layer, I created a layer mask and inverted it to black. I then selected the layer mask, and painted with white on those parts of the image where I wanted the leaves to show from the under-exposed image (with the adjusted luminance levels). Here is what my layer mask looked like when I was done:
When you compare the detail of this version to the semi-manual approach from Photomatix, you will see that this version is more detailed. Take a look:
Here is the final result:
Ghosting and Photomatix Pro 4
Ghosting happens in HDR images when something moves. For example, leaves in a tree blow in the wind and are captured in different positions in the different exposures. When those exposures are merged and tonemapped, the ghosting appears.
Ideally, when photographing trees, I want to do so when the wind is still. But that is not always possible, especially when I am out of town. But there are solutions to this problem.
Here are the three images I used on what was a low contrast day. I spaced the exposures one stop apart, auto-bracketed.
There was a soft breeze blowing, so I knew I would have some issues to overcome, as the Spanish moss was swaying back and forth. And as you will see below, I also had some leaves movings, which caused ghosting.
Here is a closeup detail of a section that shows the ghosting:
There are two ways to go about resolving this issue. The first one I want to discuss is using Photomatix Pro 4′s semi-manual Reduce Ghosting Artifacts command. Shortly after you drop your files into Photomatix Pro 4, you will see this menu:
Select that option and hit the Preprocess button on the bottom. You will next be greeted by this menu:
This window gives you the opportunity to select multiple areas of your image that contain ghosting. It’s easy to do, too. The first step, as the directions indicate, is to drag with your cursor, a border around the area you want to select. You can adjust the brightness and size of the image with the sliders on the bottom so that you can see your outline more easily. Here is my initial selection:
Then you must do the second step of Control-clicking or right-clicking inside the area to mark it as ghosted. This is required before you select another area in your image:
Your dotted white line now becomes a solid white line and you can now preview the deghosting:
So here is the result of the deghosting, which you can compare with the image detail I showed you previously which had no deghosting:
There is some improvement, but not enough. So this leaves us with the second approach, which is a full-manual approach. This involves using one of the separate exposures as a layer in Photoshop. In this case, the under-exposed image was my choice because it was just one stop under-exposed. I want this exposure because it uses a quicker shutter speed, with the result that the leaves and Spanish moss are less blurred.
Before I loaded this under-exposed image as a layer, I made some adjustments in Photoshop so that the luminance levels of the leaves were approximately the same as the HDR image. After I loaded the image as a layer, I created a layer mask and inverted it to black. I then selected the layer mask, and painted with white on those parts of the image where I wanted the leaves to show from the under-exposed image (with the adjusted luminance levels). Here is what my layer mask looked like when I was done:
When you compare the detail of this version to the semi-manual approach from Photomatix, you will see that this version is more detailed. Take a look:
Here is the final result:
