Thanks for the fast responses. Tim, you're right I did have my lambda parameters the wrong way round. Fixing up the order had no effect on the speed (platform is x64 win7).
Ian, I was basing my code off Fredrik Lundh post on comparing images. http://effbot.org/zone/pil-comparing-images.htm Terry, I will try replacing the pow function next. -- http://mail.python.org/mailman/listinfo/python-list
