fix decimal rescale values causing Decimal data frame

[bpinsard]

I ran into this bug using pydicom 0.9.7 and some Siemens Files
RescaleSlope and RescaleIntercept are returned as Decimal.

> /home_local/bpinsard/.virtualenvs/processing_virtenv/lib/python2.6/site-packages/nibabel/analyze.py(578)set_data_dtype()
>     577             raise HeaderDataError(
> --> 578                 'data dtype "%s" not recognized' % datatype)
>     579         dtype = self._data_type_codes.dtype[code]
> 
> ```
> ```

dtype being object because Decimal

[matthew-brett]

Thanks for that. Do you have a DICOM header we can test against? If you do, and we can't make it public for the tests, we can work something out, I am sure, by putting the data somewhere private.

[bpinsard]

For this fix and the other I encountered the problems with ADNI dataset, so I do not think this can be released without their consent... what do you think we can do?

[matthew-brett]

OK - thanks - that's a good point. I guess we could do two things. We could put the data in a private repository somewhere so it is not publicly shared, but we can run tests against it, given some (rarely given) permission, or we could make another header that is the same as one of the standard ones we have except for this feature. What do you think?

[moloney]

I added some anonymized test data from a user who ran into this issue.

[matthew-brett]

Excellent - thanks for doing that.