##########################################################################/
+'''Snapshot (image) comparison script.
+'''
+
+
import sys
import os.path
import optparse
import math
import operator
-import Image
-import ImageChops
-import ImageEnhance
+from PIL import Image
+from PIL import ImageChops
+from PIL import ImageEnhance
thumb_size = 320, 320
-def _compare(ref_image, src_image, delta_image):
- import subprocess
- p = subprocess.Popen([
- 'compare',
- '-metric', 'AE',
- '-fuzz', '%u%%' % options.fuzz,
- '-dissimilarity-threshold', '1',
- ref_image, src_image, delta_image
- ], stderr=subprocess.PIPE)
- _, stderr = p.communicate()
- try:
- return int(stderr)
- except ValueError:
- return 0xffffffff
+class Comparer:
+ '''Image comparer.'''
+ def __init__(self, ref_image, src_image, alpha = False):
+ self.ref_im = Image.open(ref_image)
+ self.src_im = Image.open(src_image)
-def compare(ref_image, src_image, delta_image):
- ref_im = Image.open(ref_image)
- src_im = Image.open(src_image)
+ # Ignore
+ if not alpha:
+ self.ref_im = self.ref_im.convert('RGB')
+ self.src_im = self.src_im.convert('RGB')
- ref_im = ref_im.convert('RGB')
- src_im = src_im.convert('RGB')
+ self.diff = ImageChops.difference(self.src_im, self.ref_im)
- diff = ImageChops.difference(src_im, ref_im)
+ def write_diff(self, diff_image, fuzz = 0.05):
+ # make a difference image similar to ImageMagick's compare utility
+ mask = ImageEnhance.Brightness(self.diff).enhance(1.0/fuzz)
+ mask = mask.convert('L')
- mask = ImageEnhance.Brightness(diff).enhance(100.0/options.fuzz)
- mask = mask.convert('L')
+ lowlight = Image.new('RGB', self.src_im.size, (0xff, 0xff, 0xff))
+ highlight = Image.new('RGB', self.src_im.size, (0xf1, 0x00, 0x1e))
+ diff_im = Image.composite(highlight, lowlight, mask)
- lowlight = Image.new('RGB', src_im.size, (0xff, 0xff, 0xff))
- highlight = Image.new('RGB', src_im.size, (0xf1, 0x00, 0x1e))
- delta_im = Image.composite(highlight, lowlight, mask)
+ diff_im = Image.blend(self.src_im, diff_im, 0xcc/255.0)
+ diff_im.save(diff_image)
- delta_im = Image.blend(src_im, delta_im, 0xcc/255.0)
- delta_im.save(delta_image)
+ def precision(self):
+ # See also http://effbot.org/zone/pil-comparing-images.htm
+ h = self.diff.histogram()
+ square_error = 0
+ for i in range(1, 256):
+ square_error += sum(h[i : 3*256: 256])*i*i
+ rel_error = float(square_error*2 + 1) / float(self.diff.size[0]*self.diff.size[1]*3*255*255*2)
+ bits = -math.log(rel_error)/math.log(2.0)
+ return bits
- # See also http://effbot.org/zone/pil-comparing-images.htm
- # TODO: this is approximate due to the grayscale conversion
- h = diff.convert('L').histogram()
- ae = sum(h[255 * options.fuzz // 100 + 1 : 256])
- return ae
+ def ae(self):
+ # Compute absolute error
+ # TODO: this is approximate due to the grayscale conversion
+ h = self.diff.convert('L').histogram()
+ ae = sum(h[int(255 * fuzz) + 1 : 256])
+ return ae
def surface(html, image):
help="output filename [default: %default]")
optparser.add_option(
'-f', '--fuzz',
- type="int", dest="fuzz", default=5,
- help="fuzz percentage [default: %default]")
+ type="float", dest="fuzz", default=0.05,
+ help="fuzz ratio [default: %default]")
optparser.add_option(
'--overwrite',
action="store_true", dest="overwrite", default=False,
or not os.path.exists(delta_image) \
or (os.path.getmtime(delta_image) < os.path.getmtime(ref_image) \
and os.path.getmtime(delta_image) < os.path.getmtime(src_image)):
- compare(ref_image, src_image, delta_image)
+
+ comparer = Comparer(ref_image, src_image)
+ comparer.write_diff(delta_image, fuzz=options.fuzz)
html.write(' <tr>\n')
surface(html, ref_image)