Added Image.evaluate_images method

docs/changes.rst

@@ -1,13 +1,29 @@
 Wand Changelog
 ==============
 
+.. _changelog-0.7:
+
+0.7 series
+~~~~~~~~~~
+
+
+.. _changelog-0.7.0:
+
+Version 0.7.0
+-------------
+
+Unreleased.
+
+ - Added :meth:`Image.evaluate_images() <wand.image.BaseImage.evaluate_images>` method.
+
+
 .. _changelog-0.6:
 
 0.6 series
 ~~~~~~~~~~
 
 
-.. _changelog-0.6.12:
+.. _changelog-0.6.13:
 
 Version 0.6.13
 --------------

tests/image_methods_test.py

@@ -780,6 +780,14 @@ def test_evaluate_user_error():
             img.evaluate(operator='set', value=1.0, channel='Not a channel')
 
 
+def test_evaluate_images():
+    with Image(filename='hald:3') as img:
+        with img.clone() as i:
+            img.image_add(i)
+        with img.evaluate_images(operator='add') as nue:
+            assert nue != img
+
+
 def test_export_pixels():
     with Image(filename='hald:2') as img:
         img.depth = 8  # Not need, but want to match import.

wand/image.py

@@ -4869,6 +4869,32 @@ def evaluate(self, operator=None, value=0.0, channel=None):
                 library.MagickSetImageChannelMask(self.wand, channel_mask)
         return r
 
+    def evaluate_images(self, operator=None):
+        """Create a new image by applying arithmetic operation between all
+        images loaded in the image-stack.
+
+        For example::
+
+           with Image() as img:
+                img.read(filename='first.png')
+                img.read(filename='second.png')
+                first.evaluate_images('add')
+                first.save(filename='sum.png')
+
+        :param operator: Type of operation to calculate.
+        :type operator: :const:`EVALUATE_OPS`
+
+        .. versionadded:: 0.7.0
+        """
+        assertions.string_in_list(EVALUATE_OPS, 'wand.image.EVALUATE_OPS',
+                                  operator=operator)
+        self.iterator_reset()
+        idx_op = EVALUATE_OPS.index(operator)
+        result = library.MagickEvaluateImages(self.wand, idx_op)
+        if not result:
+            self.raise_exception()
+        return Image(image=BaseImage(result))
+
     def export_pixels(self, x=0, y=0, width=None, height=None,
                       channel_map="RGBA", storage='char'):
         """Export pixel data from a raster image to