stdev

Name

stdev - calculation of local standard deviation

Syntax

 stdev <inimage> <outimage> [<dx> [<dy>]]

Description

stdev calculates and returns the standard deviation in a local window of size dx * dy. The border is also processed, calculating the standard deviation over the part of the window that is defined.

 output(x,y) = sqrt(SUM(sqr(input(x,y)-
                        mean(x,y)))/windowsize)

dx is the horizontal window size, default value 3. dy is the vertical window size, default value dx.

Restrictions

inimage must have bands with pixel type unsigned byte. If dx or dy are even, they are increased by one. dx and dy should be positive.

Author

Tor Lønnestad, BLAB, Ifi, UiO.

Examples

 stdev mona.img monaStd.img
 stdev mona.img monaStd.img 15
 stdev mona.img monaStd.img 5 9

Id

$Id: stdev.c,v 1.24 1997/01/10 16:15:09 svein Exp $