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47372Re: What is the actual Field of View?

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  • Erik Krause
    Jan 10, 2011
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      Am 10.01.2011 21:59, schrieb engstrom_henrik:
      > But I really would like to be proven wrong here, it could solve a lot
      > of problems. I have uploaded some test images, I hope they can be
      > viewed correctly;
      > http://www.flickr.com/photos/21287457@N05/
      > - 01_hf_pattern is an extremely high-frequency pattern (256x256
      > pixels) used as reference.

      This is a real extreme example indeed. However, it is of purely
      theoretical use, since (I think) Nyquist theorem will prohibit that you
      ever get this.

      It is not possible to rotate your 01_hf_pattern example at the same size
      without loosing information. This is because a pixel which is in between
      a black and a white pixel will be grey, no matter what interpolator you
      choose (except nearest neighbor, where you get an aliasing pattern).
      This most probably is due to Nyquist theorem again.

      But if you enlarge and rotate the image you don't loose much, since now
      there is more than one pixel to display a black-white boundary. If you
      do it in gimp you need to first enlarge, then rotate. Panotools does it
      in one step. Interesting that the worst and fastest interpolator -
      nearest neighbor (actually not an interpolator but a pixel picker) -
      yields the sharpest result in this case (albeit with aliasing steps).

      A comparison of the "classical" panotools interpolators is on

      The "new" ones feature adaptive kernel sizes which avoid aliasing while

      Erik Krause
      Offenburger Str. 33
      79108 Freiburg
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