Fun with Focus Stacking
One of the features of Photoshop CS4 is Focus Stacking via Auto Align and Auto Blend. They are generally used for panoramas but can also be used to expand depth of field. (Focus stacking is where you take a series of photos with different focus points and then let software build an image with everything in focus. This is particularly interesting with macro work.)
This image is the result of that technique.
This was created via Photoshop using 16 images. The images racked the focus from front to back starting with this image …
Note the focus is on the front of the toy. Sixteen images were then taken until I had everything in focus. That is every part of the toy was in focus in one or more of the 16 images. Here is the last image.
Now the back of the toy is in focus but not the front. (This did not require 16 shots. It just took that many to make sure.)
If you look closely at the finished result (top photo) you’ll note that there are some errors. (Along the curve of the stool and around the top of the smoke stack.) Those can be fixed by playing with the layer masks Auto Blend creates. It just wasn’t worth doing for this example.
How to do this (which I learned from Popular Photography) …
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Take the shots with a constant exposure.
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Rack through the focus from front to back. Make sure to overlap focus.
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Synchronize your settings when the files are converted. (WB, and all that.)
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From bridge pull them into CS4 as separate layers.
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Select all the layers and run Auto Align on them.
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Select all the layers and run Auto Blend on them.
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Save result
Pretty simple. But it didn’t work for me until I did a few other things. (I’m not sure which one did the trick.)
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Optimize Photoshop’s memory usage (80% of max).
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Give it plenty of scratch disk.
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Set the image mode to 8 bit. This halves the size of the file right away and is probably the thing that made it work.
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Crop the excess from the Auto Align.
Those last two shrink the size of the merge pretty significantly.
Fun stuff.
