make the bad alpha feature opt-in

glue/viewers/image/composite_array.py

@@ -29,6 +29,7 @@ def __init__(self, **kwargs):
 
         self._first = True
         self._mode = 'color'
+        self._allow_bad_alpha = False
 
     @property
     def mode(self):
@@ -148,10 +149,14 @@ def __call__(self, bounds=None):
                 if hasattr(layer['cmap'], 'get_bad'):
                     bad_rgba = layer['cmap'].get_bad().tolist()
                     bad_color = bad_rgba[:3]
-                    bad_alpha = bad_rgba[3]
-                    layer_cmap = layer['cmap'].with_extremes(
-                        bad=bad_color + [layer['alpha']]
-                    )
+                    bad_alpha = bad_rgba[3:]
+
+                    if self._allow_bad_alpha:
+                        bad_rgba = bad_color + bad_alpha
+                    else:
+                        bad_rgba = bad_color + [layer['alpha']]
+
+                    layer_cmap = layer['cmap'].with_extremes(bad=bad_rgba)
                 else:
                     layer_cmap = layer['cmap']
 
@@ -176,8 +181,9 @@ def __call__(self, bounds=None):
                     # Use traditional alpha compositing
                     alpha_plane = layer['alpha'] * plane[:, :, 3]
 
-                    # ensure "bad" alpha is preserved:
-                    alpha_plane[~np.isfinite(data)] *= bad_alpha
+                    if self._allow_bad_alpha:
+                        # ensure "bad" alpha is preserved:
+                        alpha_plane[~np.isfinite(data)] *= bad_alpha
 
                     plane[:, :, 0] = plane[:, :, 0] * alpha_plane
                     plane[:, :, 1] = plane[:, :, 1] * alpha_plane