Transparently store numpy arrays in ColorLut

src/PIL/ImageFilter.py

@@ -19,6 +19,11 @@ from __future__ import division
 
 import functools
 
+try:
+    import numpy
+except ImportError:  # pragma: no cover
+    numpy = None
+
 
 class Filter(object):
     pass
@@ -334,25 +339,40 @@ class Color3DLUT(MultibandFilter):
 
         # Hidden flag `_copy_table=False` could be used to avoid extra copying
         # of the table if the table is specially made for the constructor.
-        if kwargs.get('_copy_table', True):
-            table = list(table)
+        copy_table = kwargs.get('_copy_table', True)
+        items = size[0] * size[1] * size[2]
+        wrong_size = False
 
-        # Convert to a flat list
-        if table and isinstance(table[0], (list, tuple)):
-            table, raw_table = [], table
-            for pixel in raw_table:
-                if len(pixel) != channels:
-                    raise ValueError("The elements of the table should have "
-                                     "a length of {}.".format(channels))
-                for color in pixel:
-                    table.append(color)
+        if numpy and isinstance(table, numpy.ndarray):
+            if copy_table:
+                table = table.copy()
 
-        if len(table) != channels * size[0] * size[1] * size[2]:
+            if table.shape in [(items * channels,), (items, channels),
+                               (size[2], size[1], size[0], channels)]:
+                table = table.reshape(items * channels)
+            else:
+                wrong_size = True
+
+        else:
+            if copy_table:
+                table = list(table)
+
+            # Convert to a flat list
+            if table and isinstance(table[0], (list, tuple)):
+                table, raw_table = [], table
+                for pixel in raw_table:
+                    if len(pixel) != channels:
+                        raise ValueError(
+                            "The elements of the table should "
+                            "have a length of {}.".format(channels))
+                    table.extend(pixel)
+
+        if wrong_size or len(table) != items * channels:
             raise ValueError(
                 "The table should have either channels * size**3 float items "
                 "or size**3 items of channels-sized tuples with floats. "
-                "Table size: {}x{}x{}. Table length: {}".format(
-                    size[0], size[1], size[2], len(table)))
+                "Table should be: {}x{}x{}x{}. Actual length: {}".format(
+                    channels, size[0], size[1], size[2], len(table)))
         self.table = table
 
     @staticmethod