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THRESMINERREQVAR

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

NAME

thresMinErrEqVar - minimum error thresholdingwith equal variances.

SYNTAX

#include <xite/threshold.h>

int thresMinErrEqVar( histogram h, int tinit );

DESCRIPTION

thresMinErrEqVarcalculates the threshold value by usingthe minimum error thresholding technique with equal variancesas in Gonzalez and Wintz.Initially, the threshold value t is set according to tinit.

0 <= tinit <= 255, then t = tinit
tinit = -1, then t = the average of all the pixels
tinit = -2, then t = the result from thresRidCal(h)

Then, iteratively, the threshold is set to the average ofthe mean of the pixels below the threshold, and themean of the pixels above the threshold , plus acompensation factor depending on the variance of thedistribution. This variance is the average of the variancebelow and above the threshold. When the threshold valueremains constant, iteration terminates.

The actual thresholding is not performed, see theroutine "threshold".

REFERENCE

Gonzales, Rafael C & Wintz, Paul: "Digital Image Processing"Addison-Wesley, 1977.

RETURN VALUE

The threshold value. Pixel values up to, and including,the return value, is below the threshold.

AUTHOR

Olav Borgli, Fritz Albregtsen, BLAB, ifi, UiO

ID

$Id: thresMinErr.c,v 1.25 1997/03/17 13:45:07 svein Exp $

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