Fix direct colormap

napari/_vispy/layers/image.py

@@ -323,11 +323,14 @@ def downsample_texture(
     "r8": np.dtype(np.uint8),
     "r16": np.dtype(np.uint16),
     "r32f": np.dtype(np.float32),
-    None: np.dtype(np.float32),
 }
 
 _DTYPE_TO_VISPY_FORMAT = {v: k for k, v in _VISPY_FORMAT_TO_DTYPE.items()}
 
+# this is moved after reverse mapping is defined
+# to always have non None values in _DTYPE_TO_VISPY_FORMAT
+_VISPY_FORMAT_TO_DTYPE[None] = np.dtype(np.float32)
+
 
 def get_dtype_from_vispy_texture_format(format_str: str) -> np.dtype:
     """Get the numpy dtype from a vispy texture format string.

napari/_vispy/layers/labels.py

@@ -401,7 +401,7 @@
     if use_selection:
         keys = np.full((1, 1), selection, dtype=vispy_texture_dtype)
         values = np.zeros((1, 1, 4), dtype=vispy_texture_dtype)
-        values[0, 0] = color_dict[selection]
+        values[0, 0] = color_dict.get(selection, color_dict[None])
         return keys, values, False
 
     if empty_val is _UNSET:
@@ -524,6 +524,7 @@
                 interpolation='nearest',
             )
             self.node.shared_program['LUT_shape'] = key_texture.shape
+            self.node.shared_program['color_count'] = len(color_dict)
         else:
             self.node.cmap = VispyColormap(*colormap)