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[Bug 706407] Re: Remapping creates color bands in gradients

 

You're right, setting the camera response (Ra,Rb,Rc,Rd,Re) parameters to
0 solved the problem.

These parameters come from a lens profile that I generated earlier using
Hugin, by optimizing a "calibration" panorama. I'm not sure how to parse
these 5 parameters, but judging by the banding artifacts it seems like
the response correction is very significant. Is this to be expected? The
lens is a Samyang 8mm fisheye on an APS-C Nikon. The lens profile was
generated by optimizing over 9 photos with high overlap, taken outdoors
under essentially constant lighting.

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https://bugs.launchpad.net/bugs/706407

Title:
  Remapping creates color bands in gradients

Status in Hugin - Panorama Tools GUI:
  New

Bug description:
  The nona component of Hugin introduces color banding artifacts while
  remapping images. Smooth gradients in the source image show as jagged
  bands in the remapped image.

  Here's a typical example, remapping a single fisheye image into Panini General:
    Source image: http://tau.ac.il/~tromer/misc/hugin-banding-bug/TEST.JPG
    Hugin project: http://tau.ac.il/~tromer/misc/hugin-banding-bug/TEST-panini.pto (attached)
    Result image: http://tau.ac.il/~tromer/misc/hugin-banding-bug/TEST-panini.jpg

  Look at the sky in the top right corner. It's smooth in the source, but badly banded and jagged in the result.
  (Please ignore the pixelated blob on the left, it's blurred for privacy.)

  The above happens with current hugin hg and libpano13 svn, as well as
  Fedora 14's packaged versions. The artifact does not seem
  significantly affected by the choice of projection or by the nona
  interpolation mode set in Hugin.





References