PanoTools:
Re: PTGui 5.7 - how to use the antialiasing filters ?
Thomas Rauscher 2006-Feb-20 15:07:25
Hello Thomas,
on Monday, February 20, 2006, 13:48:57 you wrote:
TK> Is there some kind of a rule of thumb for using the antialiasing
TK> filters that are now accessible in PTGui 5.7?
I think it is always a good idea to use them, since the reproduction
is better (not so high tendency to ring artefacts like with sinc1024)
and if you scale down the image, at least in some parts, they avoid
aliasing.
If you look at the functions plot and think of what they mean, you can
read a lot out of it. The width of the center part produces the
blurriness. If the function is widened the filter uses more pixels to
the average and the images gets blurred. If the filter has negative
values it will do some sharpening and can produce echos.
The box filter uses exactly the values of the surrounding pixels so
this produces the same results as the nearest neighbor, if no resizing
is involved. The triangle filter produces a linear interpolation
between two values -> bilinear interpolation.