[ITK Community] [Insight-users] Why is the Normalized Correlation Metric inverted?

[Jonas Beuke]

Hi all,

I'm comparing images by using itkNormalizedCorrelationImageToImageMetric 
as a similarity metric. As far as I can see it implements exactly the 
Pearson product-moment correlation coefficient except for the line 117 
"const RealType denom = -1.0 * vcl_sqrt(sff * smm);". This line, as far 
as I understand it, inverts the correlation so -1 is a perfect positive 
correlation between the two images. What is the purpose of this?

Greetings,
Jonas
_____________________________________
Powered by www.kitware.com

Visit other Kitware open-source projects at
http://www.kitware.com/opensource/opensource.html

Kitware offers ITK Training Courses, for more information visit:
http://www.kitware.com/products/protraining.php

Please keep messages on-topic and check the ITK FAQ at:
http://www.itk.org/Wiki/ITK_FAQ

Follow this link to subscribe/unsubscribe:
http://www.itk.org/mailman/listinfo/insight-users