Merge 01fb382 into 800448d

hyperspy/signal.py

@@ -3095,9 +3095,13 @@ def change_dtype(self, dtype):
                     "It is only possibile to change to %s." %
                     ddtype)
             self.data = rgb_tools.rgbx2regular_array(self.data)
-            self.get_dimensions_from_data()
+            self.axes_manager._append_axis(
+                size=self.data.shape[-1],
+                scale=1,
+                offset=0,
+                name="RGB index",
+                navigate=False,)
             self.metadata.Signal.record_by = "spectrum"
-            self.axes_manager[-1 + 2j].name = "RGB index"
             self._assign_subclass()
             return
         else:

hyperspy/tests/signal/test_rgb.py

@@ -1,5 +1,5 @@
 import numpy as np
-from nose.tools import assert_true, raises
+import nose.tools as nt
 
 from hyperspy.misc import rgb_tools
 import hyperspy.api as hs
@@ -26,12 +26,14 @@ def test_torgb(self):
     def test_touint(self):
         self.im.change_dtype("uint8")
         np.testing.assert_array_equal(self.s.data, self.im.data)
+        nt.assert_equal(len(self.im.axes_manager._axes), 3)
+        nt.assert_equal(self.im.axes_manager.signal_axes[0].name, "RGB index")
 
-    @raises(AttributeError)
+    @nt.raises(AttributeError)
     def test_wrong_bs(self):
         self.s.change_dtype("rgba16")
 
-    @raises(AttributeError)
+    @nt.raises(AttributeError)
     def test_wrong_rgb(self):
         self.im.change_dtype("rgb8")
 
@@ -58,10 +60,10 @@ def test_touint(self):
         self.im.change_dtype("uint16")
         np.testing.assert_array_equal(self.s.data, self.im.data)
 
-    @raises(AttributeError)
+    @nt.raises(AttributeError)
     def test_wrong_bs(self):
         self.s.change_dtype("rgba8")
 
-    @raises(AttributeError)
+    @nt.raises(AttributeError)
     def test_wrong_rgb(self):
         self.im.change_dtype("rgb16")