Members of Adobe Creative Cloud had access to Photoshop CC. A great feature in this version is the Shake Reduction filter. It analyzes the image looking for the direction the camera ‘shook’ and corrects for the movement. The results can be dramatic. In this post I’ll talk about how I used this filter to sharpen images a recent trip to Europe including those of the famous Irish Clonycavan ‘bog man’.
Shaky images result from camera movement during exposure. I run into this when I am shooting in low light and want to keep the ISO down to quiet the noise. I also see it in images I shot from a moving tour bus.
As a general rule, I shoot using a shutter speed at least 1/x of a second where x is the actual focal length of the lens you are using. For example, when using a telephoto lens, lets say with a 200 mm focal length I shoot no slower than 1/200th of a second shutter speed. This is usually sufficient to obtain reasonably, but not necessarily critically sharp images with good hand-held camera technique in good light. Note that you must use the actual focal length of the lens and not in a cropped sensor effective focal length in the calculation. Cameras with lens stabilization technology allow you to break the shutter speed rule at times and I recommend using it whenever shooting hand-held.
The Shake Reduction filter was especially helpful for museum shots where I couldn’t obtain a fast enough shutter speed in ambient light and a flash was not allowed or would have ruined the appearance of the custom lighting for the piece. On the trip I brought my older Nikon Coolpix 80 rather than my DSLR for convenience. This resulted in a bit more shaking and sensor noise than I liked, but it was great to leave the 20 pounds of gear at home! As you will see, this filter was a life saver and has prompted me to revisit past ‘shaky’ images.
As an aside, I created a Photoshop Action and called it from Lightroom using a Photoshop Droplet to automate applying the filter on a large number of pictures. The filter set its own parameters for each image, and I was generally pleased with the results. I did use the filter manually when the automatic settings produced poor results, especially with museum images containing text placards. I’ll talk about that problem a litte later.
Using the Filter
You invoke the filter from the Photoshop Filter -> Sharpen menu. It opens the current image and automatically applies its effect. You might want to create a duplicate image layer to apply the filter to because Photoshop alters the background layer by default.
Here is the filter interface. Click on this and other images to view them in larger sizes:
The first thing you will notice is the rectangular dashed box with the bulls eye in the center. This box encloses the default Blur Estimation Region used by the filter and is located automatically on a region that contains content suitable for measurement. This is often in the center, but can be elsewhere. Within this region the filter evaluates the image for the amount and direction of the shaking. If it cannot find a suitable region it will display a warning message and require you to identify the region manually.
Once the filter has a suitable region it determines the amount of camera shake then automatically applies the effect. In essence, it ‘reverses’ the shaking, resulting in a sharper image. I have found that in many cases it does a very good job including the default 30% values for both Smoothing and Artifact Suppression.
Here is a before and after comparison for the Hydra image in the filter interface example. I took this hand-held from a moving tour bus and in spite of the bright light the image is still blurred. Normally I would consider discarding this image but it has become a keeper after using the filter.
As before, click to enlarge.
If your image does not find a suitable region in automatic mode, or you want to manually intervene you can add one or more of your own using the Blur Estimation Region tool shown in the upper left-hand corner of the filter window. If it does Automatically locate a Blur Estimation Region you can have it automatically add other regions by clicking the Add suggested Blur Trace control in the Advanced section of the interface. Regions with texture and contrast are best.
You can move an existing region by clicking and dragging on the bulls eye and re-size a region using the controls at the edges and corners of the box. Each time you add or move a region the filter will execute based upon all of the estimation regions. You can enable and disable regions in the Advanced section of the interface to refine the sharpening.
Try using the Trace tool located under the Blur Estimation Region tool to set the length and direction of a straight shaking motion. It is worth a bit of trial and error to get used to how this tool works, though I did not find a significant improvement using it for my images.
You can manually set the blur trace parameters in the dialog box to the right if the automatically selected values do not produce the results you are looking for. These consist of the Blur Trace Bounds that tell the filter how far from a given point to examine for evidence of shaking.
The Source Noise setting, which defaults to Auto, is used to indicate how much noise is in the image, affecting the behavior of the filter. As with the other settings, I encourage you to experiment using different values to determine which is appropriate for troublesome images. Having said this, the Shake Reduction filter works best on images with little or no noise.
Next is the amount of smoothing that the filter will do in order to reduce over sharpening. I often set this value a bit lower than the default resulting in slightly sharper images.
You can also customize the filter settings for each Blur Estimation Region and toggle each region on and off in the Advanced section of the filter interface to compare the results.
Finally, as shown on the Hydra example is the Artifact Suppression Value. Artifact Suppression takes a more complex look at an image than Smoothing and attempts to reduce any noise-based artifacts generated during the process. I leave this turned off or reduce it most of the time as I find the softening effect is too great for images with low noise.
Once you are satisfied, click OK to close the filter and return to Photoshop. If you have applied the filter to a duplicate background layer you can now blend that with the layer below using the layer Fill value to refine the amount of sharpening in the final image.
Refrain from Pixel Peeping
Before I forget to mention it, this filter is not necessarily perfect. It will, however tempt you to evaluate the image at 100% resolution. But it is highly unlikely that anyone viewing your images will be ‘pixel peeping’. I recommend that you evaluate the image at the size you expect it to be displayed or printed..
Problems with Text
I have discovered that the filter can be less accurate when an image contains text such as on a museum placard. Here is an example using a shot of an Irish Wolf Hound in the Dublin National Archaeology or as locals call it, the ‘Stuffed Animal’ Museum.
Here is the original image.
Below is the image with the filter applied using automatic settings. In this case the filter automatically centered the Blur Estimation Region box on the larger text placard located at the bottom center of the image.
This automatic attempt is much too sharp. Also notice the ghosting around edges of some of the items. I found that the filter routinely centered on areas of text in my museum images with less than satisfactory effects.
The next image is a comparison of the before and after manually setting the filter parameters and moving the Blur Estimation Region to the dog’s fur. Notice how the sharpness is slightly improved and the scene still appears natural. This image is a good compromise between shake reduction and visible artifacts. It took a minute or two working with the filter settings to achieve it. Compare different objects in the image to see the effect.
As a reminder, you can click the image for a larger version.
The Irish Clonycavan Man and More Comparisons
Here are additional comparisons that illustrate the use of the filter with automatic settings. The differences can be subtle, but you should be able to spot them in the larger versions.
The first is of the Irish Clonycavan ‘bog’ Man of National Geographic fame, discovered in recent years. I shot it under the well designed ambient lighting. Notice the improvement in the hair and skin texture in the ‘after’ image to the right.
Here is a now extinct Irish Moose in the Irish Natural History Museum, or as the locals call it, the ‘stuffed animal’ museum.
The filter performed very well in the following brooch comparison.
Moving on to Romania…
As with the other indoor images, I shot this mural hand-held using ambient light. As with the other comparisons, the right-hand image is the result of only using the Shake Reduction filter.
This vase and carving below are in the Peles Castle; an amazing attraction if you are ever in the area!
Finally, here is a before and after comparison of a panel from a Roman column in Bucharest.
As always, Happy Shooting!
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