stvar

Name

stvar - local variance

Syntax

stvar [-t] <inimage> <outimage> <deltax> <deltay> <k>

Description

Local variable threshold.

 t(x,y) = k*s(x,y) + u(x,y)
      r(x,y) = b(x,y) - t(x,y) + 128
 [-t] r(x,y) = if( b(x,y) >= t(x,y)) then 255 else 0

 r(x,y)  = output image
 u(x,y)  = mean component
 s(x,y)  = st. dev component
 b(b,y)  = pixel value in (x,y)

 deltax  = Local area width
 deltay  = Local area height

Options

-t: Threshold the result.

Restrictions

input must have bands with pixel type unsigned byte.

Reference

Wayne Niblack: An introduction to Digital Image Processing

Author

Otto Milvang

Id

$Id: stvar.c,v 1.27 1997/01/10 16:17:34 svein Exp $