Confusion over mi vs mi2 metric

[dzenanz]

There is a discrepancy between converting metric from enum to string:
https://github.com/ANTsX/ANTs/blob/v2.5.1/Examples/itkantsRegistrationHelper.h#L253-L256
and string to enum:
https://github.com/ANTsX/ANTs/blob/v2.5.1/Examples/itkantsRegistrationHelper.hxx#L145-L152

I am new to ANTs, so I don't know what is the best way to fix it.

[ntustison]

Thanks. I'll take a look.

[ntustison]

Okay, so these two functions serve separate purposes and aren't meant to be used inversely. StringToMetricType() is basically used for reading from the command line. Mattes MI has always been prioritized in ANTs over JointHistogram MI which is why we relegated the latter to "mi2." The other function, GetMetricAsString() is strictly used for printing to the screen. I added a bit of clarification in the latter here. If you feel that this ambiguity needs to be clarified further, just let me know if you have any ideas.