File size: 9,572 Bytes
18dd6ad
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
# Copyright (c) OpenMMLab. All rights reserved.
import io
import os.path as osp
from pathlib import Path

import cv2
import numpy as np
from cv2 import (IMREAD_COLOR, IMREAD_GRAYSCALE, IMREAD_IGNORE_ORIENTATION,
                 IMREAD_UNCHANGED)

from annotator.uniformer.mmcv.utils import check_file_exist, is_str, mkdir_or_exist

try:
    from turbojpeg import TJCS_RGB, TJPF_BGR, TJPF_GRAY, TurboJPEG
except ImportError:
    TJCS_RGB = TJPF_GRAY = TJPF_BGR = TurboJPEG = None

try:
    from PIL import Image, ImageOps
except ImportError:
    Image = None

try:
    import tifffile
except ImportError:
    tifffile = None

jpeg = None
supported_backends = ['cv2', 'turbojpeg', 'pillow', 'tifffile']

imread_flags = {
    'color': IMREAD_COLOR,
    'grayscale': IMREAD_GRAYSCALE,
    'unchanged': IMREAD_UNCHANGED,
    'color_ignore_orientation': IMREAD_IGNORE_ORIENTATION | IMREAD_COLOR,
    'grayscale_ignore_orientation':
    IMREAD_IGNORE_ORIENTATION | IMREAD_GRAYSCALE
}

imread_backend = 'cv2'


def use_backend(backend):
    """Select a backend for image decoding.

    Args:
        backend (str): The image decoding backend type. Options are `cv2`,
        `pillow`, `turbojpeg` (see https://github.com/lilohuang/PyTurboJPEG)
        and `tifffile`. `turbojpeg` is faster but it only supports `.jpeg`
        file format.
    """
    assert backend in supported_backends
    global imread_backend
    imread_backend = backend
    if imread_backend == 'turbojpeg':
        if TurboJPEG is None:
            raise ImportError('`PyTurboJPEG` is not installed')
        global jpeg
        if jpeg is None:
            jpeg = TurboJPEG()
    elif imread_backend == 'pillow':
        if Image is None:
            raise ImportError('`Pillow` is not installed')
    elif imread_backend == 'tifffile':
        if tifffile is None:
            raise ImportError('`tifffile` is not installed')


def _jpegflag(flag='color', channel_order='bgr'):
    channel_order = channel_order.lower()
    if channel_order not in ['rgb', 'bgr']:
        raise ValueError('channel order must be either "rgb" or "bgr"')

    if flag == 'color':
        if channel_order == 'bgr':
            return TJPF_BGR
        elif channel_order == 'rgb':
            return TJCS_RGB
    elif flag == 'grayscale':
        return TJPF_GRAY
    else:
        raise ValueError('flag must be "color" or "grayscale"')


def _pillow2array(img, flag='color', channel_order='bgr'):
    """Convert a pillow image to numpy array.

    Args:
        img (:obj:`PIL.Image.Image`): The image loaded using PIL
        flag (str): Flags specifying the color type of a loaded image,
            candidates are 'color', 'grayscale' and 'unchanged'.
            Default to 'color'.
        channel_order (str): The channel order of the output image array,
            candidates are 'bgr' and 'rgb'. Default to 'bgr'.

    Returns:
        np.ndarray: The converted numpy array
    """
    channel_order = channel_order.lower()
    if channel_order not in ['rgb', 'bgr']:
        raise ValueError('channel order must be either "rgb" or "bgr"')

    if flag == 'unchanged':
        array = np.array(img)
        if array.ndim >= 3 and array.shape[2] >= 3:  # color image
            array[:, :, :3] = array[:, :, (2, 1, 0)]  # RGB to BGR
    else:
        # Handle exif orientation tag
        if flag in ['color', 'grayscale']:
            img = ImageOps.exif_transpose(img)
        # If the image mode is not 'RGB', convert it to 'RGB' first.
        if img.mode != 'RGB':
            if img.mode != 'LA':
                # Most formats except 'LA' can be directly converted to RGB
                img = img.convert('RGB')
            else:
                # When the mode is 'LA', the default conversion will fill in
                #  the canvas with black, which sometimes shadows black objects
                #  in the foreground.
                #
                # Therefore, a random color (124, 117, 104) is used for canvas
                img_rgba = img.convert('RGBA')
                img = Image.new('RGB', img_rgba.size, (124, 117, 104))
                img.paste(img_rgba, mask=img_rgba.split()[3])  # 3 is alpha
        if flag in ['color', 'color_ignore_orientation']:
            array = np.array(img)
            if channel_order != 'rgb':
                array = array[:, :, ::-1]  # RGB to BGR
        elif flag in ['grayscale', 'grayscale_ignore_orientation']:
            img = img.convert('L')
            array = np.array(img)
        else:
            raise ValueError(
                'flag must be "color", "grayscale", "unchanged", '
                f'"color_ignore_orientation" or "grayscale_ignore_orientation"'
                f' but got {flag}')
    return array


def imread(img_or_path, flag='color', channel_order='bgr', backend=None):
    """Read an image.

    Args:
        img_or_path (ndarray or str or Path): Either a numpy array or str or
            pathlib.Path. If it is a numpy array (loaded image), then
            it will be returned as is.
        flag (str): Flags specifying the color type of a loaded image,
            candidates are `color`, `grayscale`, `unchanged`,
            `color_ignore_orientation` and `grayscale_ignore_orientation`.
            By default, `cv2` and `pillow` backend would rotate the image
            according to its EXIF info unless called with `unchanged` or
            `*_ignore_orientation` flags. `turbojpeg` and `tifffile` backend
            always ignore image's EXIF info regardless of the flag.
            The `turbojpeg` backend only supports `color` and `grayscale`.
        channel_order (str): Order of channel, candidates are `bgr` and `rgb`.
        backend (str | None): The image decoding backend type. Options are
            `cv2`, `pillow`, `turbojpeg`, `tifffile`, `None`.
            If backend is None, the global imread_backend specified by
            ``mmcv.use_backend()`` will be used. Default: None.

    Returns:
        ndarray: Loaded image array.
    """

    if backend is None:
        backend = imread_backend
    if backend not in supported_backends:
        raise ValueError(f'backend: {backend} is not supported. Supported '
                         "backends are 'cv2', 'turbojpeg', 'pillow'")
    if isinstance(img_or_path, Path):
        img_or_path = str(img_or_path)

    if isinstance(img_or_path, np.ndarray):
        return img_or_path
    elif is_str(img_or_path):
        check_file_exist(img_or_path,
                         f'img file does not exist: {img_or_path}')
        if backend == 'turbojpeg':
            with open(img_or_path, 'rb') as in_file:
                img = jpeg.decode(in_file.read(),
                                  _jpegflag(flag, channel_order))
                if img.shape[-1] == 1:
                    img = img[:, :, 0]
            return img
        elif backend == 'pillow':
            img = Image.open(img_or_path)
            img = _pillow2array(img, flag, channel_order)
            return img
        elif backend == 'tifffile':
            img = tifffile.imread(img_or_path)
            return img
        else:
            flag = imread_flags[flag] if is_str(flag) else flag
            img = cv2.imread(img_or_path, flag)
            if flag == IMREAD_COLOR and channel_order == 'rgb':
                cv2.cvtColor(img, cv2.COLOR_BGR2RGB, img)
            return img
    else:
        raise TypeError('"img" must be a numpy array or a str or '
                        'a pathlib.Path object')


def imfrombytes(content, flag='color', channel_order='bgr', backend=None):
    """Read an image from bytes.

    Args:
        content (bytes): Image bytes got from files or other streams.
        flag (str): Same as :func:`imread`.
        backend (str | None): The image decoding backend type. Options are
            `cv2`, `pillow`, `turbojpeg`, `None`. If backend is None, the
            global imread_backend specified by ``mmcv.use_backend()`` will be
            used. Default: None.

    Returns:
        ndarray: Loaded image array.
    """

    if backend is None:
        backend = imread_backend
    if backend not in supported_backends:
        raise ValueError(f'backend: {backend} is not supported. Supported '
                         "backends are 'cv2', 'turbojpeg', 'pillow'")
    if backend == 'turbojpeg':
        img = jpeg.decode(content, _jpegflag(flag, channel_order))
        if img.shape[-1] == 1:
            img = img[:, :, 0]
        return img
    elif backend == 'pillow':
        buff = io.BytesIO(content)
        img = Image.open(buff)
        img = _pillow2array(img, flag, channel_order)
        return img
    else:
        img_np = np.frombuffer(content, np.uint8)
        flag = imread_flags[flag] if is_str(flag) else flag
        img = cv2.imdecode(img_np, flag)
        if flag == IMREAD_COLOR and channel_order == 'rgb':
            cv2.cvtColor(img, cv2.COLOR_BGR2RGB, img)
        return img


def imwrite(img, file_path, params=None, auto_mkdir=True):
    """Write image to file.

    Args:
        img (ndarray): Image array to be written.
        file_path (str): Image file path.
        params (None or list): Same as opencv :func:`imwrite` interface.
        auto_mkdir (bool): If the parent folder of `file_path` does not exist,
            whether to create it automatically.

    Returns:
        bool: Successful or not.
    """
    if auto_mkdir:
        dir_name = osp.abspath(osp.dirname(file_path))
        mkdir_or_exist(dir_name)
    return cv2.imwrite(file_path, img, params)