fractile
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Name
fractile - noise reduction filtering
Syntax
fractile <inimage> <outimage> fractile [<dx> [<dy>]]
Description
Fractile noise filtering with window dx * dy
using the histogram updating technique.
Sorts all pixels within the window and picks the
fractile pixel. fractile = 1/dx/dy gives min-filter,
fractile = 0.5 gives median filter, and
fractile = 1.0-1/dx/dy gives max-filter.
fractile must be non-negative and maximum 1.0.
Default value for dx is 3, for dy it is dx.
Reference
Huang, Yang and Tang:
"A Fast Two-Dimensional Median Filtering Algorithm"
IEEE Trans. Ac., Speech, and Signal Proc, Vol ASSP-27,
No.1, Feb.1979
See also
pseudomedian3x3(1), median(1), minarea(1), maxarea(1)
Restrictions
Accepts only images with pixel type unsigned byte.
dx and dy must be larger than 0.
Author
Tor Lønnestad, BLAB, Ifi, UiO
Modified
Otto Milvang, BLAB, Ifi, UiO
Examples
fractile mona.img mona.30.img 0.3
fractile mona.img mona.40.img 0.4 7
fractile mona.img mona.60.img 0.6 7 5
Id
$Id: fractile.c,v 1.22 1997/03/07 12:52:08 svein Exp $