1 # Copyright (c) 2011 The Chromium Authors. All rights reserved. 2 # Use of this source code is governed by a BSD-style license that can be 3 # found in the LICENSE file. 4 5 """Compare two images for equality.""" 6 7 from PIL import Image 8 from PIL import ImageChops 9 10 11 def Compare(file1, file2, **kwargs): 12 """Compares two images to see if they're identical. 13 14 Args: 15 file1: path to first image to compare 16 file2: path to second image to compare 17 kwargs: unused for this operator 18 19 Returns: 20 None if the images are identical 21 A tuple of (errorstring, image) if they're not 22 """ 23 kwargs = kwargs # unused parameter 24 25 im1 = Image.open(file1) 26 im2 = Image.open(file2) 27 28 if im1.size != im2.size: 29 return ("The images are of different size (%s vs %s)" % 30 (im1.size, im2.size), im1) 31 32 diff = ImageChops.difference(im1, im2) 33 34 if max(diff.getextrema()) != (0, 0): 35 return ("The images differ", diff) 36 else: 37 return None 38
