47372Re: What is the actual Field of View?
- Jan 10, 2011Am 10.01.2011 21:59, schrieb engstrom_henrik:
> But I really would like to be proven wrong here, it could solve a lotThis is a real extreme example indeed. However, it is of purely
> of problems. I have uploaded some test images, I hope they can be
> viewed correctly;
> - 01_hf_pattern is an extremely high-frequency pattern (256x256
> pixels) used as reference.
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
Offenburger Str. 33
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