title: SimpleITK N4BiasFieldCorrection, not working with any data type
body: <p>Just installed the latest version of SimpleITK and I'm trying to run a simple code as:</p>
  
  <pre><code>im = sitk.ReadImage('img.nii.gz')
  im_bin = sitk.ReadImage('img_bin.nii.gz')
  im_bfc = sitk.N4BiasFieldCorrection(im, im_bin)
  </code></pre>
  
  <p>the error is </p>
  
  <pre><code>RuntimeError: Exception thrown in SimpleITK N4BiasFieldCorrection: /scratch/dashboards/SimpleITK-OSX10.7-intel-pkg/SimpleITK/Code/Common/include/sitkDualMemberFunctionFactory.hxx:214:
  sitk::ERROR: Pixel type: 64-bit signed integer is not supported in 2D byN3itk6simple32N4BiasFieldCorrectionImageFilterE
  </code></pre>
  
  <p>I tried with casting to different type, int, float, signed, unsigned, and I tried with 2d and 3d images. I tried as well to use <a href="https://itk.org/SimpleITKDoxygen07/html/N4BiasFieldCorrection_8py-example.html" rel="nofollow">https://itk.org/SimpleITKDoxygen07/html/N4BiasFieldCorrection_8py-example.html</a> 
  And the error has always been the same. Other modules of SimpleITK appears to work. 
  Any idea? Can you reproduce the error?<br>
  Thanks!</p>