How to correct perspective and lens distortion in digital photos
britneysimpson
Tuesday June 27, 2006 (05:00 PM GMT)
By: Nathan Willis
Warped horizon lines and bent skyscrapers are just as disheartening to
the travel photographer as the demonic "red eye" effect. Red eye
correction is commonplace in software today, but you don't have to live
with distortion either. Free software can correct lens- and
perspective-distortion, turning the fishbowl look into the landscape as
you remember it. And even if you don't have vacation pictures that need
a new perspective, the same technique can come in handy elsewhere --
such as for extracting undistorted textures from a photo to use in a
game or 3-D model. Here's how to do it.
Most people never bother with fixing perspective distortion in their
photos, unless they find a particularly egregious one -- and then they
try the pull-on-the-corners Perspective tool in Photoshop or the GIMP,
often with miserable results. On the other hand, panoramic photography
aficionados must fix the distortion in their images, or else they won't
stitch together correctly. As a result, the panoramic photo apps all
have perspective correction tools, and they are top-notch.
Don't be scared off by the obscurity of the software category here; you
don't have to know or care anything about creating panoramas in order
to use this one function. I'll walk you through it, and tell you
everything you need to ignore.
http://software.newsforge.com/software/06/06/19/215245.shtml?tid=131