Path: utzoo!censor!geac!alias!imax!dave
From: dave@imax.com (Dave Martindale)
Newsgroups: comp.graphics
Subject: Re: Image restoration
Keywords: image restore warp
Message-ID: <1990Jul18.162340.12905@imax.com>
Date: 18 Jul 90 16:23:40 GMT
References: <4187@tahoe.unr.edu> <1990Jul15.061617.19425@comspec.uucp> <48999@seismo.CSS.GOV>
Distribution: usa
Organization: Imax Systems Corporation, Oakville Canada
Lines: 17

In article <48999@seismo.CSS.GOV> black@beno.CSS.GOV (Mike Black) writes:
>I'm in need of an algorithm to undo the effect of a 90 degree field of view
>lens.  I tried a dual-axis third order polynomial fit and it didn't handle
>the corners very well.

First, you have to know the distortion characteristics of the lens.
Designers *try* to build lenses with minimal distortion, even if the
field of view is 90 degrees, so the distortion that remains is one
of the compromises that had to be accepted to get something else in
the design.  Thus, every design of a wide-angle lens will have
different distortion characteristics.

Or was this lens designed as a fisheye?

Anyway, once you know what the distortion you are trying to correct
looks like, you can see how well various polynomials (or other functions)
will fit the curve.