PanoTools NG:
Re: Some more tests on Optimal Cubefaces.
Hans Nyberg 2008-Nov-01 14:18:01
--- In #removed#, "Erik Krause" <erik.krause@...> wrote:
>
> Am Friday, October 31, 2008 um 23:36 schrieb Hans Nyberg:
>
> > I have discovered that Pano2VR seems to have problems with downsizing.
> > The 1904 is softer than the CubicConverter version.
>
> This may be due to the fact that Pano2VR uses a non-sharpening anti-
> aliasing interpolator. On
> http://wiki.panotools.org/Anti-aliasing_interpolators the Filters
> with ID 18 and higher are sharpening ones (the deeper the
> "depression" on both sides of the peak the more).
>
> I don't know what kind of interpolator CubicConverter uses, but the
> result of a not anti-aliased downsize always gives a sharper
> impression because pixel "jaggies" subjectively look sharper (but
> increase shimmering in the resulting pano - if the viewer doesn't
> anti-alias itself).
CubicConverter uses Bicubic which seems to be called Cubic in wiki.
Why not use the Bicubic definition if it is the same. I never heard anyone call it just cubic.
Photoshop today has 3 Bicubic versions.
From what I understand Pano2VR uses Mitchell as default but Mitchell softens the
cubefaces slightly compared to CubiConverter. They need 0,4 100% unsharp mask to get
back to the same quality if you do an conversion with editing cubefaces and convert back
to equirectangular. This does not make sense after reading your comment as Mitchell
should have the same effect as Cubic.
Lazcos 3 gives normally same quality as CubicConverter but I found that I had to get up
to Blackman/sinc Filter to get the same when doing downsizing.
Hans
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