Add a scale function to expand or contract a PIL image by a factor factorpassed in argument.

PIL/Image.py

@@ -1547,6 +1547,26 @@ class Image(object):
 
         return self._new(self.im.resize(size, resample))
 
+    def scale(self, factor, resample = NEAREST):
+        """
+        Returns a rescaled image by a specific factor given in parameter.
+        A factor greater than 1 expands the image, between 0 and 1 contracts the
+        image.
+
+        :param factor: The expansion factor, as a float.
+        :param resample: An optional resampling filter. Same values possible as
+           in the PIL.Image.resize function.
+        :returns: An :py:class:`~PIL.Image.Image` object.
+        """
+        if factor == 1:
+            return self._new(self.im)
+        elif factor <= 0:
+            raise ValueError("the factor must be greater than 0")
+        else:
+            size = (int(round(factor * self.width)),
+                    int(round(factor * self.height)))
+            return self.resize(size, resample)
+
     def rotate(self, angle, resample=NEAREST, expand=0):
         """
         Returns a rotated copy of this image.  This method returns a