Merge pull request #2468 from bmorris3/cmap-bad-preserve-alpha

Preserve alpha while compositing with cmap.set_bad
glue-viz · Feb 28, 2024 · 785e29b · 785e29b
2 parents 5f38baf + 822a9dc
commit 785e29b
Showing 1 changed file with 16 additions and 6 deletions.
diff --git a/glue/viewers/image/composite_array.py b/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):
@@ -146,10 +147,16 @@ def __call__(self, bounds=None):
                 # ensure "bad" values have the same alpha as the
                 # rest of the layer:
                 if hasattr(layer['cmap'], 'get_bad'):
-                    bad_color = layer['cmap'].get_bad().tolist()[:3]
-                    layer_cmap = layer['cmap'].with_extremes(
-                        bad=bad_color + [layer['alpha']]
-                    )
+                    bad_rgba = layer['cmap'].get_bad().tolist()
+                    bad_color = bad_rgba[:3]
+                    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']
 
@@ -162,8 +169,7 @@ def __call__(self, bounds=None):
                 # Check what the smallest colormap alpha value for this layer is
                 # - if it is 1 then this colormap does not change transparency,
                 # and this allows us to speed things up a little.
-                if layer_cmap(CMAP_SAMPLING)[:, 3].min() == 1:
-
+                if layer_cmap(CMAP_SAMPLING)[:, 3].min() == 1 and (not self._allow_bad_alpha or bad_alpha == 1):
                     if layer['alpha'] == 1:
                         img[...] = 0
                     else:
@@ -175,6 +181,10 @@ def __call__(self, bounds=None):
                     # Use traditional alpha compositing
                     alpha_plane = layer['alpha'] * plane[:, :, 3]
 
+                    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
                     plane[:, :, 2] = plane[:, :, 2] * alpha_plane