Update image.py (#140)

This commit solves the following issues:
- The second argument of method read_band() of ImageArray is now consistent with that of SpyFile classes, which otherwise was producing warnings or errors.
- read_datum() method of ImageArray class used a deprecated call (np.asscalar), which was giving errors. It is now replaced by the "self" call itself which returns what is supposed to be returned by the method.

Author: mhmdjouni

spectral/image.py

@@ -118,11 +118,11 @@ def __getitem__(self, args):
     def _parent_getitem(self, args):
         return np.ndarray.__getitem__(self, args)
 
-    def read_band(self, i):
+    def read_band(self, band):
         '''
         For compatibility with SpyFile objects. Returns arr[:,:,i].squeeze()
         '''
-        return np.asarray(self[:, :, i].squeeze())
+        return np.asarray(self[:, :, band].squeeze())
 
     def read_bands(self, bands):
         '''For SpyFile compatibility. Equivlalent to arr.take(bands, 2)'''
@@ -161,7 +161,7 @@ def read_subimage(self, rows, cols, bands=None):
 
     def read_datum(self, i, j, k):
         '''For SpyFile compatibility. Equivlalent to arr[i, j, k]'''
-        return np.asscalar(self[i, j, k])
+        return self[i, j, k]
 
     def load(self):
         '''For compatibility with SpyFile objects. Returns self'''