Applying calibrated geometrical distortion to an image ?

Posted by Alan Hewat on
URL: http://imagej.273.s1.nabble.com/Applying-calibrated-geometrical-distortion-to-an-image-tp5001968.html

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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