| # Copyright (c) 2011 The Chromium Authors. All rights reserved. |
| # Use of this source code is governed by a BSD-style license that can be |
| # found in the LICENSE file. |
| |
| """Compare two images for equality.""" |
| |
| from PIL import Image |
| from PIL import ImageChops |
| |
| |
| def Compare(file1, file2, **kwargs): |
| """Compares two images to see if they're identical. |
| |
| Args: |
| file1: path to first image to compare |
| file2: path to second image to compare |
| kwargs: unused for this operator |
| |
| Returns: |
| None if the images are identical |
| A tuple of (errorstring, image) if they're not |
| """ |
| kwargs = kwargs # unused parameter |
| |
| im1 = Image.open(file1) |
| im2 = Image.open(file2) |
| |
| if im1.size != im2.size: |
| return ("The images are of different size (%s vs %s)" % |
| (im1.size, im2.size), im1) |
| |
| diff = ImageChops.difference(im1, im2) |
| |
| if max(diff.getextrema()) != (0, 0): |
| return ("The images differ", diff) |
| else: |
| return None |
