1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
|
# -*- coding: utf-8 -*-
# Copyright 2014-2016 OpenMarket Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import logging
from io import BytesIO
from PIL import Image as Image
logger = logging.getLogger(__name__)
EXIF_ORIENTATION_TAG = 0x0112
EXIF_TRANSPOSE_MAPPINGS = {
2: Image.FLIP_LEFT_RIGHT,
3: Image.ROTATE_180,
4: Image.FLIP_TOP_BOTTOM,
5: Image.TRANSPOSE,
6: Image.ROTATE_270,
7: Image.TRANSVERSE,
8: Image.ROTATE_90,
}
class Thumbnailer:
FORMATS = {"image/jpeg": "JPEG", "image/png": "PNG"}
def __init__(self, input_path):
self.image = Image.open(input_path)
self.width, self.height = self.image.size
self.transpose_method = None
try:
# We don't use ImageOps.exif_transpose since it crashes with big EXIF
image_exif = self.image._getexif()
if image_exif is not None:
image_orientation = image_exif.get(EXIF_ORIENTATION_TAG)
self.transpose_method = EXIF_TRANSPOSE_MAPPINGS.get(image_orientation)
except Exception as e:
# A lot of parsing errors can happen when parsing EXIF
logger.info("Error parsing image EXIF information: %s", e)
def transpose(self):
"""Transpose the image using its EXIF Orientation tag
Returns:
Tuple[int, int]: (width, height) containing the new image size in pixels.
"""
if self.transpose_method is not None:
self.image = self.image.transpose(self.transpose_method)
self.width, self.height = self.image.size
self.transpose_method = None
# We don't need EXIF any more
self.image.info["exif"] = None
return self.image.size
def aspect(self, max_width, max_height):
"""Calculate the largest size that preserves aspect ratio which
fits within the given rectangle::
(w_in / h_in) = (w_out / h_out)
w_out = min(w_max, h_max * (w_in / h_in))
h_out = min(h_max, w_max * (h_in / w_in))
Args:
max_width: The largest possible width.
max_height: The larget possible height.
"""
if max_width * self.height < max_height * self.width:
return max_width, (max_width * self.height) // self.width
else:
return (max_height * self.width) // self.height, max_height
def _resize(self, width, height):
# 1-bit or 8-bit color palette images need converting to RGB
# otherwise they will be scaled using nearest neighbour which
# looks awful
if self.image.mode in ["1", "P"]:
self.image = self.image.convert("RGB")
return self.image.resize((width, height), Image.ANTIALIAS)
def scale(self, width, height, output_type):
"""Rescales the image to the given dimensions.
Returns:
BytesIO: the bytes of the encoded image ready to be written to disk
"""
scaled = self._resize(width, height)
return self._encode_image(scaled, output_type)
def crop(self, width, height, output_type):
"""Rescales and crops the image to the given dimensions preserving
aspect::
(w_in / h_in) = (w_scaled / h_scaled)
w_scaled = max(w_out, h_out * (w_in / h_in))
h_scaled = max(h_out, w_out * (h_in / w_in))
Args:
max_width: The largest possible width.
max_height: The larget possible height.
Returns:
BytesIO: the bytes of the encoded image ready to be written to disk
"""
if width * self.height > height * self.width:
scaled_height = (width * self.height) // self.width
scaled_image = self._resize(width, scaled_height)
crop_top = (scaled_height - height) // 2
crop_bottom = height + crop_top
cropped = scaled_image.crop((0, crop_top, width, crop_bottom))
else:
scaled_width = (height * self.width) // self.height
scaled_image = self._resize(scaled_width, height)
crop_left = (scaled_width - width) // 2
crop_right = width + crop_left
cropped = scaled_image.crop((crop_left, 0, crop_right, height))
return self._encode_image(cropped, output_type)
def _encode_image(self, output_image, output_type):
output_bytes_io = BytesIO()
fmt = self.FORMATS[output_type]
if fmt == "JPEG":
output_image = output_image.convert("RGB")
output_image.save(output_bytes_io, fmt, quality=80)
return output_bytes_io
|
