Sunday, February 1, 2004

Correcting lens distortion with ImageAlign Pro


By David Gewirtz

Each month, we set out to bring you an interesting plug-in that can improve your photographs. This month, we've brought you a product all the way from New Zealand (which, to us in America, seems quite far away and quite romantic).

The product is ImageAlign Pro, shown in Figure A.


The ImageAlign Pro interface is quite straightforward. (click for larger image)

ImageAlign, from a company with the improbable name of Grasshopper, corrects both camera tilt and lens curvature distortions in a single pass. The company claims that the resultant image actually matches what the eye itself sees.

The plug-in (which is also available as a stand-alone program) will do the following on-the-fly transformations: barrel correction, pincushion correction, rotation, vertical perspective shift, horizontal perspective shift, vertical skew, horizontal skew, and a simple scaling effect.

What we found quite neat was the combination of effects. For example, you can take a badly distorted picture like the one shown in Figure B, and rework it.


This image from our clip art collection has a nasty distortion problem. (click for larger image)

In this example, I first used the barrel correction to fix the bridge as best as I could. Then, before sending the image back to Photoshop, I also used the perspective shift to push the bottom of the image away a bit, bringing the top closer. The result can be seen in Figure C.


Although the picture's far from perfect, the distortion's mostly gone. (click for larger image)

Most of the effects found in ImageAlign Pro can be done in Photoshop itself, although with a huge amount of work, and without anywhere near the real-time preview possible by making multiple distortion changes at once.

One other thing we liked was that you could save your adjustments to a setting, so if you'd taken a whole series of shots from one location, you could apply those settings and make your distortion removal process all that much easier.

The product comes with a well-written PDF manual and tutorial (which we only found after tinkering with the product for this's installed in your All Programs menu).

Unfortunately, at $199 (US), this is not an inexpensive tool, and that means most amateur photographers probably won't want to add it to their collection. On the other hand, if you're a professional and use Photoshop regularly, this one $200 investment will likely save you a whole heck of a lot of hours.

There was some internal debate here as to whether to rate this product a three or a four out of five. In terms of the product's performance, it was clearly a four. But because it was quite pricey, we initially thought we'd take away some points. But after serious consideration, it became clear that for the audience this is intended, that of the more serious photographer, the usefulness of the tool compensates for the somewhat hefty price. We rate it four lenses out of five.