Reduce color fringing in multi source compositing

CHANGELOG.md

@@ -8,6 +8,7 @@
 - Do not create needless alpha bands in the multi source ([#1451](../../pull/1451))
 - Infer DICOM file size, when possible ([#1448](../../pull/1448))
 - Swap styles faster in the frame viewer ([#1452](../../pull/1452))
+- Reduce color fringing in multi source compositing ([#1456](../../pull/1456))
 
 ### Bug Fixes
 - Fix an issue with compositing sources in the multi source caused by alpha range ([#1453](../../pull/1453))

large_image/tilesource/base.py

@@ -1731,6 +1731,10 @@ def getRegion(self, format: Union[str, Tuple[str]] = (TILE_FORMAT_IMAGE, ), **kw
                 'width': max(self.tileWidth, 4096),
                 'height': max(self.tileHeight, 4096)}
             kwargs['tile_offset'] = {'auto': True}
+        resample = True
+        if 'resample' in kwargs:
+            kwargs = kwargs.copy()
+            resample = kwargs.pop('resample', None)
         tileIter = TileIterator(self, format=TILE_FORMAT_NUMPY, resample=None, **kwargs)
         if tileIter.info is None:
             pilimage = PIL.Image.new('RGB', (0, 0))
@@ -1767,6 +1771,8 @@ def getRegion(self, format: Union[str, Tuple[str]] = (TILE_FORMAT_IMAGE, ), **kw
             dtype = cast(np.ndarray, image).dtype
             image = _imageToPIL(cast(np.ndarray, image), mode).resize(
                 (outWidth, outHeight),
+                getattr(PIL.Image, 'Resampling', PIL.Image).NEAREST
+                if resample is None else
                 getattr(PIL.Image, 'Resampling', PIL.Image).BICUBIC
                 if outWidth > regionWidth else
                 getattr(PIL.Image, 'Resampling', PIL.Image).LANCZOS)

sources/multi/large_image_source_multi/__init__.py

@@ -1029,7 +1029,7 @@ def _getTransformedTile(self, ts, transform, corners, scale, frame, crop=None):
         if output['maxWidth'] <= 0 or output['maxHeight'] <= 0:
             return None, 0, 0
         srcImage, _ = ts.getRegion(
-            region=region, output=output, frame=frame,
+            region=region, output=output, frame=frame, resample=None,
             format=TILE_FORMAT_NUMPY)
         # This is the region we actually took in our source coordinates, scaled
         # for if we took a low res version
@@ -1149,7 +1149,7 @@ def _addSourceToTile(self, tile, sourceEntry, corners, scale):
             self.logger.debug('getRegion: ts: %r, region: %r, output: %r', ts, region, output)
             sourceTile, _ = ts.getRegion(
                 region=region, output=output, frame=sourceEntry.get('frame', 0),
-                format=TILE_FORMAT_NUMPY)
+                resample=None, format=TILE_FORMAT_NUMPY)
         else:
             sourceTile, x, y = self._getTransformedTile(
                 ts, transform, corners, scale, sourceEntry.get('frame', 0),