rank

Name

rank - noise reduction filter

Syntax

 #include <xite/median.h>

 int rank( IBAND input, IBAND output, int rank,
    int dx, int dy );

Description

rank filters the input band into the output band using a rank filter with window size dx*dy. Even values of dx and dy are increased by one. Every input pixel is replaced by the rank-th pixel in a sorted vector containg all pixels in the dx*dy window. rank=1 gives the min filter, rank=dx*dy/2 gives the median filter, and rank = dx*dy gives the max filter.

Uses histogram updating when moving horizontally from pixel to pixel, like the method used in-

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.

Return value

 0 => ok
 1 => bad pixel type input band
 2 => bad pixel type output band
 3 => bad rank value (outide 1..dx*dy)
 4 => bad dx value (less than 1 or greater than xsize)
 5 => bad dy value (less than 1 or greater than ysize)

Author

Tor L|nnestad, BLAB, ifi, UiO

Id

$Id: rank.c,v 1.22 1997/01/10 16:09:01 svein Exp $