thresMinErrEqVar
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Name
thresMinErrEqVar - minimum error thresholding
with equal variances.
Syntax
#include <xite/threshold.h>
int thresMinErrEqVar( histogram h, int tinit );
Description
thresMinErrEqVar calculates the threshold value by using
the minimum error thresholding technique with equal variances
as 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 of
the mean of the pixels below the threshold, and the
mean of the pixels above the threshold , plus a
compensation factor depending on the variance of the
distribution. This variance is the average of the variance
below and above the threshold. When the threshold value
remains constant, iteration terminates.
The actual thresholding is not performed, see the
routine "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 $