Perspective/aberation correction

I had previously covered a couple of tools I used to prepare photos for textures, but I removed this as one of the tools is not now available. Which is a shame, really, because ImageAlign Pro was a great tool created here in Godzone, and I still find it indispensable for perspective correction.
My original tutorial discussed my workflow which started with a free tool called PTLens, which automatically corrected the barrel distortion created by using a wide-angle lens, and then moved to ImageAlign Pro to correct the perspective.

PT Lens uses a database of camera/lens profiles to automate the correction process, so last month when I was testing a new lens I bought for my son, I went looking for a profile for the lens. Instead, I found a new version of PT Lens, no longer free but good value at US$25. The new PT Lens has now incorporated perspective correction, so it is a nice cheap alternative to ImageAlign Pro.

PT Lens, like ImageAlign Pro, comes in both a standalone version and a PhotoShop Plugin. I've always used the standalone version, as I don't use PhotoShop, but I'm very pleased that the PT Lens plugin works in Picture Publisher, which handles some, but not all, PhotoShop plugins. So now all the preparation work can be done inside Picture Publisher, saving me a lot of work.

One problem with the Picture Publisher/PT Lens plugin combination is that Picture Publisher doesn't retain the required photo meta-data, so the plugin can't determine the camera, lens, and focal length. However the standalone version picks this up, and I understand that PhotoShop does so as well. I still find it easier to work with the plugin though, as my camera/lens combination is normally the same, and I can read the focal length from the image properties and enter it into the plugin.

Here's a typical image in Picture Publisher. It displays the sort of distortion you get from shooting at a wide angle (the curved edges) and perspective distortion from having the aim the camera upwards to get the whole thing in the frame.



Although in the past I've used the standalone version to batch-process all the images for a particular project, now I can do all the work inside my imaging software -- PTLens is available from the Effects menu.




So here's the PT Lens tool in action. Normally this opens full-screen, so you can get a good look at your image, but I've reduced the window quite a lot here.



Note that the Barrel-Pincushion correction default to the last settings here, but the standalone and PhotoShop versions can automatically determine the Make, Model, Lens and focal length if you wish. Since I normally only use the one camera/lens, I just need to type in the focal length. For focal lengths greater than 35 using this particular lens, I can turn off this correction, as it makes no difference to the final image.



A quick tweak of the Vertical Perspective and Rotate settings fix the perspective in a few seconds. Pressing 'OK' returns to Picture Publisher with the corrections applied. In the standalone version, you'd Save the corrected image at this point.

There are some limitations compared to ImageAlign Pro -- IA Pro includes a Skew correction, as well, which is very handy, but Picture Publisher can do this quite well itself.

PT Lens is available from Epaperpress.com. There is a trial version available.
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