Options for Focus Stacking Software
Last week I discussed merging multiple shots of the same subject taken at different focus distances to create images with extended depth of field using a technique known as focus stacking. This week I'll look at several software programs to help you do it.
Starting with the CS4 release, Adobe added focus stacking directly into Photoshop. It wasn't until CS5 though that it was really ready for prime time in my opinion. If you create a stack in Bridge of all images to be merged, you can open the set easily in Photoshop. The command is oddly called "Open in Photoshop Layers" rather than something more obvious but this actually makes sense when you realize it's really only the first step of the process. What you get is a single Photoshop document with one layer for each of your source images.
The next step is to select all of your document layers and go to Edit >> Auto-Align Layers to compensate for any slight camera movement between frames as well as adjust for minor magnification ratio differences due to lens extension that comes from changing focus. Just select the "Auto" option here and don't worry about the other choices. When this finishes, you can proceed to the Edit >> Auto-Blend Layers menu command. The dialog gives you the choice to create a panorama or a stacked image blend. For focus stacking, you obviously want the second choice. The "seamless tones and colors" checkbox at the bottom of the dialog should be turned on to avoid abrupt edges in the result.
Now you have to wait for the merge to complete. This is not one of the faster things Photoshop can do, so be prepared to wait if you have a number of high resolution images to merge. When Photoshop does finish, you will have a mask on each layer to control what is visible from each. This means the merge process is completely lossless and you can paint on the masks just like normal to tweak things. This isn't as easy as it might seem though as you have to be careful to have at least one layer visible at each point. If you paint black on the mask for the layer as sharpest at some point you will have a transparent spot in the composite image unless you also paint white on some other layer. To help keep an eye out for this, first create a new layer underneath all your stacked layers and fill it with neon pink or some obnoxious color that will be highly visible if it shows through at any point. This way, if you ever see that color you know you have a "hole" in your merged stack.
Helicon Focus by HeliconSoft is typically regarded as the top focus stacking option. This reputation is at least in part due to the fact that it's been around longer than the competition, but the real value of Helicon Focus goes much deeper than just that. The program runs on both Windows and Mac OS X in both 32-bit and 64-bit versions and runs multi-threaded on systems with multiple CPU cores so performance is well optimized for whatever system you want to run it on.
But all that power wouldn't be worth much if it didn't do a good job of course. Thankfully, it does a great job. As with most focus stacking programs, Helicon started out with macro shooting in mind but it can also do a great job for enhanced depth of field landscape shots. Helicon also does a better job of automatically handling movement, halos and the like during the merge process than Photoshop seems to do. Areas of low contrast tend retain more detail in Helicon than Photoshop too. You can really tell that some serious work went into creating the intelligence built into Helicon Focus.
Help is provided throughout the user interface to make the process relatively easy even for new users. The default settings seem quite good but if you find the need to tweak things you have full control over the method and options for the merge algorithm. Retouching tools allow you tweak things further by giving you the ability to paint from any source image to the final image with full undo/redo. Tabs across the top guide you through the typical workflow. All in all this is the most professional looking package out there for focus stacking.
Helicon supports just about every graphic file format out there including raw images and Photoshop PSD files. A Lightroom plug-in lets you easily integrate Helicon into your existing workflow.
My only real gripe about Helicon Focus is that it doesn't export layered Photoshop files. It would be great if you could open the merged result in Photoshop and use a mask for each layered source image to keep the merge lossless. You can save your result as a layered Adobe PSD, but not with all the source info intact. Rather than masking each layer, Helicon exports layers with transparency already baked in. As is, even with the great tools provided by HeliconSoft, once you save the output, you're pretty much committed. Even if you do notice some detail later that isn't quite right you'll have a much harder time correcting it than if you had done the merge directly in Photoshop. Make sure you really like your merge results before doing any final touchups in another program.
Helicon Focus isn't cheap but if you're serious about focus stacking it is well worth it. There's a Lite version for $115, a Pro version for $200, and a Pro X64 version for $250. If you want to save some money you can also license the Lite or Pro version on an annual basis starting at only $30 a year. The Lite version lacks the retouching brush, batch mode and other advanced features. As its name implies, Pro X64 gives you a 64-bit version in addition to the regular 32-bit Pro version so you can take full advantage of all the memory in your system. If you shoot landscape, the Pro or better version is highly recommended since you will likely need the retouch feature unless you only shoot when the wind isn't blowing.
One extremely nice feature only available in the Pro and Pro X64 versions is something called Helicon Remote that makes it a snap to shoot images for stacking. More on this next week.
For the price, CombineZP by Alan Hadley can't be beat. Unlike many tools in photography, the program is distributed under a GPL license and is completely free. The user interface may induce a flashback to the early nineties but don't let that put you off. CombineZP (and its predecessor CombineZM) can do a great job of merging focus stacked images. Given that I already own Photoshop CS5 and Helicon Focus Pro X64 I haven't done too much playing with CombineZP but even just reading through the Help file will give you a good idea of its capabilities. You'll have to persevere through the user interface, but if you do CombineZP could be a great choice.
I had set out to compare the three most commonly used focus stacking applications, CombineZP, Adobe Photoshop and Helicon Focus, but while discussing the article with a friend he mentioned a fourth option that looks quite good indeed. Until then, I wasn't aware of Zerene Stacker but it turns out to be made by a small family-owned business right here in Washington State. It runs under Windows, Mac OS X and even Linux. It reads both 8-bit and 16-bit images, it runs fast, and it produces great results.
I really like the retouching capability of Zerene Stacker. The user interface seems extremely well thought out as are the tools provided. You can easily navigate between all source images as well as output images created with different program options to take care of areas where the program may not have automatically generated the best results possible. Having said this though, you are limited to what the program will let you do. As with Helicon Focus, there's no provision to output your result as a true layered Photoshop file with masks.
Raw file handling is difficult with Zerene Stacker. You have to convert them externally to 16-bit TIFF files, and then combine the resulting image files. While this isn't overly cumbersome, it does take extra time. If you shoot raw with Zerene Stacker, make sure you convert all the files with the same settings. If you try to optimize each raw conversion separately you'll find it much more difficult to merge them.
It's also not color managed. If you work in a wide gamut color space such as ProPhoto RGB or even Adobe RGB you'll find that your images will appear somewhat washed out in the Zerene Stacker interface. Don't panic though since the program will write the color profile it finds in the input to the merged output file so when you open it in another program it will look the way it's supposed to. It's just that in Zerene Stacker itself you probably won't be too pleased with what your images look like. This might give you the impression that they're not really worth spending time on but keep in mind that they don't really look as bad as they appear. I find it frustrating that in this day and age photo editing programs aren't properly color managed. Hopefully Zerene Systems will add fix this in a future version.
Still, if you can live with its limitations, Zerene Stacker is capable of producing excellent results. The program is offered in three versions – a Student Edition for $39, a Personal Edition for $89, and a Professional Edition for $289. You might be wondering what the difference is between these other than a lot of money but the answer may surprise you. From what I can tell, the features are the same, it's just that they expect you to pay more if you are using it more and can afford it. In other words, only the licensing terms differ, not the feature set. They say they are looking at adding certain premium features to the Professional Edition in the future, but have not done so yet. The Student Edition requires that you send them an email detailing what college or institution you are attending.
There are even more programs out there capable of focus stacking but hopefully this rundown of the most popular options will at least get you started.