def get_image_narray(image_array, dim)
      if Object.const_defined?('NArray')
        @image_narray = pixel_data = NArray.to_na(image_array).reshape!(*dim[1..dim[0]])
      else
        add_msg "Can't find NArray, no image_narray created.  Please `gem install narray`"
      end
    end
def get_image_narray(image_array, dim)
      if Object.const_defined?('NArray')
        @image_narray = pixel_data = NArray.to_na(image_array).reshape!(*dim[1..dim[0]])
      else
        add_msg "Can't find NArray, no image_narray created.  Please `gem install narray`"
      end
    end
Create an narray if the NArray is available
 Tests if a file is readable, and if so, opens it.

 === Parameters

 * <tt>image_array</tt> -- Array. A vector of image data.
 * <tt>dim</tt> -- Array. The dim array from the nifti header, specifing number of dimensions (dim[0]) and dimension length of other dimensions to reshape narray into.