Re: [Algorithms] Gaussian blur kernels

[Olivier G. <gal...@po...>]

On Thu, Jul 16, 2009 at 09:56:58AM +0100, Simon Fenney wrote:
> Jon Watte wrote:
> 
> > Actually, they are both low-pass filters, so
> > downsampling-plus-upsampling is a form of blur. However, box
> > filtering (the traditional downsampling function) isn't actually all
> > that great at low-pass filtering, so it can generate aliasing, which
> > a Gaussian filter does not.
> 
> AFAICS a box filter won't "generate" aliasing, it's just that it's not
> very good at eliminating the high frequencies which cause aliasing. A
> Gaussian, OTOH, has better behaviour in this respect...

Aren't we talking about graphics here?  Vision is area sampling,
making box filters perfect for integer downsampling.  It's sound that
is point sampling and hence sensitive to high frequency aliasing.

  OG.