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RANK

Section: C Library Functions (3)
Updated: 16 Mar 1998
Index

NAME

rank - noise reduction filter

SYNTAX

#include <xite/median.h>

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

DESCRIPTION

rankfilters the input band into the output bandusing 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-thpixel in a sorted vector containg all pixelsin the dx*dy window. rank=1 gives the minfilter, rank=dx*dy/2 gives the median filter,and rank = dx*dy gives the max filter.

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

REFERENCE

Huang, Yang and Tang: "A Fast Two-DimensionalMedian 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 $

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