[Insight-users] mutual info output

[Luis Ibanez]

Hi Robert,

The output of the Mutual Information Image Metric
(or any other Image Metric in ITK for that matter)
is a float number that measures the similarity between
two images.

You are probably refering to the output of a full
registration method that uses Mutual Information
as the Image Metric.  All the registration processes
in ITK are performed in physical units. E.g. millimeters
if that's what you used for specifiying the spacing in
your input images.

Be careful, though, since ITK itself doesn't have
a notion of what physical units you are using.
We tend to assume that the values of image spacing
are expressed in millimeters simply because most
of our images are from MRI and CT of humans.

But,... people using ITK for processing confocal
microscopy images may express the units in microns
or even nanometers.  People using ITK for processing
astronomical images may use parsecs as unit of spacing.
People using ITK for satelinte image may use degrees
as unit of spacing, or maybe Kilometers.

So, to put it short: The output of the translation
components in a registration process is expressed
in the units you used for the representing the pixel
spacing of your image.


Regards,


   Luis


--------------------------------
Robert-Paul Buitendijk wrote:
> hello
> 
> the output of the mutual information metric, translationalongX and
> translationalongY, is it allways in mm?? regardong of what data you use??
> 
> tnx  Robert
> 
> 
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