Just making sure that you understand what -define filter:blur=.75 does (say): It keeps the same shape, lobes and all (so, Jinc still has exactly three lobes, and the kernel is zero at the limit of the extent of the filter). All it does, is rescale the support (without chopping anything). The "natural" support of the Jinc function is a disk of radius about 3.238. blur=.75 shrinks the disk, "pulling in" the shape, down to a disk of radius about 2.429.imaggie wrote:Just thinking on the hoof here, how does adding a small slice of a lobe compare to removing a similar amount?
Does adding a small slice soften , as I suspect, or increase the ringing due having fractionally more lobes ?
"Chopping off" or "adding bits" of lobes is not an option when enlarging more than a little, because it introduces "jump" artifacts.