PanoTools mailing list archive
|Date/Time:||Mon, 20 Feb 2006 17:33:47 +0100|
|Subject:||Re: Re: PTGui 5.7 - how to use the antialiasing filters ?|
on Monday, February 20, 2006, 17:00:23 you wrote:
>> The kernel size on my page is the radius of the kernel so the largest
>> kernel is 8x8 pixels. Its also possible to extend this size to what
>> ever you like, but I see no real advantage since the the maximum
>> contribution of a pixel beyond this radius with a gamma of 2.2 is
>> sinc(4.5 * Pi) ^ 2.2 = 0,00295 for a 8 bit image this makes 0,754 of a
>> step... so a really wide pattern of white/black pixels would be needed
>> to see any difference at all... and I doubt that this gives "better"
>> results instead of just echos in a normal image.
EK> So why are the old sinc interpolators so large?
To better perform in the zoneplate rotating test... ;)
EK> I even think I can see a difference between sinc256 and
Yes, you may notice a difference because the sinc function is windowed
by another sinc function so if the window is wider, the weights for
the nearer pixels are a little bit different.
EK> BTW.: My favourite printing program - QImage - uses so called Vector and Pyramid
EK> filters for upsampling. They are far superior to lanczos for that task. Wouldn't
EK> they be an alternative for simple resampling, too?
I will have a look at them! Maybe some day...
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