Focus stacking

[chupathingie]

soosh posted some macro shots using Zerene Stacker and that got me wondering about what open-source software was available to do the same.

So I started playing around with Enfuse, since it has an option to fuse based on contrast. It works, and it’s fairly fast, but leaves rather obvious halos around any high-contrast areas that border across different depths of field.

I got sidetracked using Enfuse to composite based on exposure (as an HDR technique) for a couple days but got back on track yesterday with the focus stacking by downloading ImageJ and a couple of plugins for depth of field compositing.

I like IMageJ so far, I’ve used the Extended Depth of Field and the Stack Focuser plugins.

I took a stack of 25 images that I focused at small increments as a test run with a 5DmkII so I could see if it could handle large image files. I started with the Extended Depth of Field plugin and ran it through using the “quick” settings. Very obvious halos, but I thought maybe the “quality” setting would look better. I let that run for over 12 hours before I decided that the plugin is just not suited for large images. It’s just too slow, but it might work well for fewer images in the stack.

Next I downloaded the Stack Focuser plugin and ran my images through it. I like this one much better, the halos are much less obvious and even when I bumped the sample size way up (I doubled the default setting from 11X11 pixels to 22X22) it still managed to combine the stack in under 10 minutes.

Final image here: http://www.flickr.com/photos/44012674@N04/5700007205/sizes/l/in/photostream/

It’s unaltered from the ImageJ output, and I did need to run the originals through align_image_stack before adding them into a stack in ImageJ. The FOV changes while changing focus will of course need to be cropped out, but I was expecting that.

Oh, and a heads-up to anyone that wants to try this… ImageJ runs with a default of 512meg allocated to the java engine (it’s java-based). If you are running large images or a large number of images through it, you might want to open that up a bit. I reset the default to use 12000meg, and wound up using almost all of that on this stack; and that was with 8-bit images. Plan accordingly if you’re going to run 16-bit through this (it will handle 16-bit, and face it… you’re going to do them that way anyway, aren’t you?).

Anyone have any focus-bracketed macro shots they wanna share for science? I’d like to see if there’s any difference in the halos between some macro subs vs my dining table setup. I tried to use high-contrast items as a stress test, so I’m expecting better results with anything that might have less dynamic range.

I’m really looking forward to some goodies from B&H now…

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