geomTfrm_LensDistortion.cpp File Reference

Read an image, correct it for radial lens discortion, and write out the corrected image. More...

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Detailed Description

Read an image, correct it for radial lens discortion, and write out the corrected image.

Author

Mitch Richling https://www.mitchr.me

Copyright

Copyright (c) 1988-2015, Mitchell Jay Richling https://www.mitchr.me All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions, and the following disclaimer.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Details

The geomTfrmRevRPoly() method uses a radial polynomial transform. This method may be used to reproduce the behavior of Imagemagick's barrel distortion transformation. In Imagemagick the following terminology and constraints are used:

• (X, Y) is the image center for both T & S
• A, B, C, & D are constants
• A+B+C+D=1 – if you don't provide D it will be computed

This is all put together on the command line something like this:

      -distort Barrel "A B C D X Y"

We can demonstrate the similar behavior between Imagemagick & this example program like this:

• Make test images

      make test_images
      ./test_images.exe

• Compute the new image with imagemagik

      rm test_images_mcgrid_fimg.tiff
      magick test_images_mcgrid.tiff -background Green -virtual-pixel Background -interpolate Bilinear -filter point -distort barrel "0.0 -0.0160 0.0" test_images_mcgrid_fimg.tiff
      start test_images_mcgrid_fimg.tiff

• Compute the new image with MRaster

      make geomTfrm_LensDistortion
      ./geomTfrm_LensDistortion.exe test_images_mcgrid.tiff
      mv geomTfrm_LensDistortion.tiff test_images_mcgrid_fmr.tiff
      start test_images_mcgrid_fmr.tiff

• Use compare aginst the two imgages

      magick compare -metric mae test_images_mcgrid_fmr.tiff test_images_mcgrid_fimg.tiff out.tiff
      start out.tiff

• Subtract the two images

      magick test_images_mcgrid_fmr.tiff test_images_mcgrid_fimg.tiff -compose Mathematics -define compose:args='0,1,-1,0' -composite out.tiff
      start out.tiff

Note the images are not identical, but they are very close.

Definition in file geomTfrm_LensDistortion.cpp.