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Fish-eye image re-mapping Outline I first published this page back in April 1999, at that time there were relatively few options available to geometrically re-map fisheye images to other types of projections. However since that time a wide variety of free and commercial tools have been developed, each have their own virtues and limitations. Interestingly it seems that much of the most flexible and best performing software utilises a current version of the "pano12.dll" transformation library that was originally designed by Helmut Dersch (but since abandoned due I beleive to legal attacks). This library is in the public domain and so is much of the software that uses it so I'll concentrate on these tools. If you aren't much of a tinkerer and would rather trade some flexibility for ease of use then PTLens from epaperpress.com (for Windows users) or LensFix from Kekus Digital (for Mac users, not free-ware unfortunately). These packages are available as Photoshop compatible plugins and feature fisheye to rectilinear conversion, geometric distortion reduction, vignetting compensation and chromatic aberration (CA) correction. The vignetting and CA correction are visual however there is a database covering popular lenses and bodies so that pre-determined distortion correction factors can be applied. If the image contains EXIF information in some case the programs will use this information
Example images Clicking on a thumbnail will yield a magnified image, use the browser back button to return.
Fish-eye mapped to rectilinear (135 degrees HAOV or approx 7.5mm/135 format equivalent lens)
Details I used a precision Photoshop/Gimp compatible freeware plug-in called Panorama Tools to perform the Fish-eye to rectilinear remapping above. The package is produced by Professor Helmut Dersch and is available for several computer platforms from http://www.path.unimelb.edu.au/~dersch/ This tool provides many remapping, distortion and illumination correction algorithms as well as an image stitching tool suited for panorama production. Expert users of this tool can also use it to neutralise colour shift and fringing that is so often apparent in rectilinear converted Fish-eye images. See Brian Caldwells excellent page "Correcting Distortion and Color Fringing" for details and an excellent tutorial at http://www.caldwellphotographic.com/TutorialsDistortionAndColorFringing.html A shareware GUI called Panorama Tools Assistant which wraps around Panorama Tools and provides visually interactive remapping is available at http://www.tawbaware.com/ptasmblr.htm Rob Studdert Design & Copyright © - Digital Image Studio 1998 |
