adierebel / Crop and resize image with aspect ratio using Pillow

11 Jul 2018 at 07:54

1	from PIL import Image
2
3	def flat( *nums ):
4	'Build a tuple of ints from float or integer arguments. Useful because PIL crop and resize require integer points.'
5
6	return tuple( int(round(n)) for n in nums )
7
8	class Size(object):
9	def __init__(self, pair):
10	self.width = float(pair[0])
11	self.height = float(pair[1])
12
13	@property
14	def aspect_ratio(self):
15	return self.width / self.height
16
17	@property
18	def size(self):
19	return flat(self.width, self.height)
20
21	def cropped_thumbnail(img, size):
22	'''
23	Builds a thumbnail by cropping out a maximal region from the center of the original with
24	the same aspect ratio as the target size, and then resizing. The result is a thumbnail which is
25	always EXACTLY the requested size and with no aspect ratio distortion (although two edges, either
26	top/bottom or left/right depending whether the image is too tall or too wide, may be trimmed off.)
27	'''
28
29	original = Size(img.size)
30	target = Size(size)
31
32	if target.aspect_ratio > original.aspect_ratio:
33	# image is too tall: take some off the top and bottom
34	scale_factor = target.width / original.width
35	crop_size = Size( (original.width, target.height / scale_factor) )
36	top_cut_line = (original.height - crop_size.height) / 2
37	img = img.crop( flat(0, top_cut_line, crop_size.width, top_cut_line + crop_size.height) )
38	elif target.aspect_ratio < original.aspect_ratio:
39	# image is too wide: take some off the sides
40	scale_factor = target.height / original.height
41	crop_size = Size( (target.width/scale_factor, original.height) )
42	side_cut_line = (original.width - crop_size.width) / 2
43	img = img.crop( flat(side_cut_line, 0, side_cut_line + crop_size.width, crop_size.height) )
44
45	return img.resize(target.size, Image.ANTIALIAS)

1	Picture = Image.open("/path/load/file.jpg")
2	Picture = cropped_thumbnail(Picture, (500, 500))
3	Picture.save("/path/save/file.jpg", "JPEG")

Comments (0)