Re: Applying calibrated geometrical distortion to an image ?

Posted by giubi on
URL: http://imagej.273.s1.nabble.com/Applying-calibrated-geometrical-distortion-to-an-image-tp5001968p5001969.html

Hi Alan,

Calibrated distortion correction is a common need in several applications.

Determine the optical geometry of your camera is not easy though. Here the
well documented MATLAB Toolbox:
http://www.vision.caltech.edu/bouguetj/calib_doc/

Here an automated undistortion example using the OpenCV C++ library:
http://www.aishack.in/2010/07/calibrating-undistorting-with-opencv-in-c-oh-yeah/

Hope it helps,
/Giuseppe


On 3 March 2013 09:33, Alan Hewat <[hidden email]> wrote:

> I have a camera instrument with a fixed geometry that produces slightly
> distorted images.
>
> I want to determine the distortion correction field, by comparing the
> distorted image with the undistorted image, eg of a grid. I then want to
> apply that calibrated correction field to any image with the same camera,
> without user interaction. I need a precise automatic correction, since the
> user must measure positions within the corrected image.
>
> I tried http://biocomp.cnb.csic.es/~iarganda/SplineDeformationGenerator/which allows a choice of distortion models with a small number of
> parameters. This works, but calibration requires an a priori choice of the
> type of distortion  (fisheye, barrel etc...) and then manual adjustment of
> the parameters to obtain what <b>appears</b> to be the least distorted
> image. It is too subjective, and difficult to obtain parameters that remove
> all distortion.
>
> Then http://biocomp.cnb.csic.es/~iarganda/bUnwarpJ/ looked promising.
> This determines the distortion field that will transform between an
> un-distorted and distorted image pair. But again it appears to be a manual
> process and I couldn't see from the tutorial how I could store the
> distortion field and automatically apply it to new images with the same
> distortion.
>
> I would have thought that calibrated distortion correction was a common
> need for many fixed geometry cameras, but couldn't find much more on the
> WWW. Any suggestions would be welcome.
>
> Alan.
>
>
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