Merge pull request #1513 from girder/faster-multi-compositing

Speed up multi source compositing in tiled cases

CHANGELOG.md

@@ -5,6 +5,7 @@
 ### Improvements
 - Improve uint16 image scaling ([#1511](../../pull/1511))
 - Read some untiled tiffs using the tiff source ([#1512](../../pull/1512))
+- Speed up multi source compositing in tiled cases ([#1513](../../pull/1513))
 
 ## 1.28.1
 

sources/multi/large_image_source_multi/__init__.py

@@ -1098,12 +1098,12 @@ def _addSourceToTile(self, tile, sourceEntry, corners, scale):
         :returns: a numpy array of the tile.
         """
         source = self._sources[sourceEntry['sourcenum']]
-        ts = self._openSource(source, sourceEntry['kwargs'])
         # If tile is outside of bounding box, skip it
         bbox = source['bbox']
         if (corners[2][0] <= bbox['left'] or corners[0][0] >= bbox['right'] or
                 corners[2][1] <= bbox['top'] or corners[0][1] >= bbox['bottom']):
             return tile
+        ts = self._openSource(source, sourceEntry['kwargs'])
         transform = bbox.get('transform')
         x = y = 0
         # If there is no transform or the diagonals are positive and there is