Use a copy of the DICOM pixel_array dataset for the DicomImage class
Use a copy of the DICOM pixel_array dataset for the DicomImage class.  Prevents ValueError when trying to do things like `self.array -= foo` in the DicomArray class.
Resolves Issue
@@ -704,7 +704,7 @@ class DicomImage(BaseImage):
if dtype is not None:
self.array = ds.pixel_array.astype(dtype)
else:
- self.array = ds.pixel_array
+ self.array = ds.pixel_array.copy()
# convert values to HU or CU: real_values = slope * raw + intercept
is_ct_storage = self.metadata.SOPClassUID.name == 'CT Image Storage'
has_rescale_tags = hasattr(self.metadata, 'RescaleSlope') and hasattr(self.metadata, 'RescaleIntercept')
