1 # GNU MediaGoblin -- federated, autonomous media hosting
2 # Copyright (C) 2011, 2012 MediaGoblin contributors. See AUTHORS.
4 # This program is free software: you can redistribute it and/or modify
5 # it under the terms of the GNU Affero General Public License as published by
6 # the Free Software Foundation, either version 3 of the License, or
7 # (at your option) any later version.
9 # This program is distributed in the hope that it will be useful,
10 # but WITHOUT ANY WARRANTY; without even the implied warranty of
11 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 # GNU Affero General Public License for more details.
14 # You should have received a copy of the GNU Affero General Public License
15 # along with this program. If not, see <http://www.gnu.org/licenses/>.
19 from exifread
import process_file
20 from exifread
.utils
import Ratio
27 from mediagoblin
.processing
import BadMediaFail
28 from mediagoblin
.tools
.translate
import pass_to_ugettext
as _
30 # A list of tags that should be stored for faster access
40 'EXIF ISOSpeedRatings',
45 def exif_image_needs_rotation(exif_tags
):
47 Returns True if EXIF orientation requires rotation
49 return 'Image Orientation' in exif_tags \
50 and exif_tags
['Image Orientation'].values
[0] != 1
53 def exif_fix_image_orientation(im
, exif_tags
):
55 Translate any EXIF orientation to raw orientation
58 - Well, it changes the image, which means we'll recompress
59 it... not a problem if scaling it down already anyway. We might
60 lose some quality in recompressing if it's at the same-size
67 if 'Image Orientation' in exif_tags
:
72 orientation
= exif_tags
['Image Orientation'].values
[0]
73 if orientation
in rotation_map
:
75 rotation_map
[orientation
])
80 def extract_exif(filename
):
82 Returns EXIF tags found in file at ``filename``
85 with
open(filename
, 'rb') as image
:
86 return process_file(image
, details
=False)
88 raise BadMediaFail(_('Could not read the image file.'))
93 Clean the result from anything the database cannot handle
95 # Discard any JPEG thumbnail, for database compatibility
96 # and that I cannot see a case when we would use it.
97 # It takes up some space too.
99 'Thumbnail JPEGInterchangeFormatLength',
101 'Thumbnail JPEGInterchangeFormat']
103 return dict((key
, _ifd_tag_to_dict(value
)) for (key
, value
)
104 in six
.iteritems(exif
) if key
not in disabled_tags
)
107 def _ifd_tag_to_dict(tag
):
109 Takes an IFD tag object from the EXIF library and converts it to a dict
110 that can be stored as JSON in the database.
113 'printable': tag
.printable
,
115 'field_type': tag
.field_type
,
116 'field_offset': tag
.field_offset
,
117 'field_length': tag
.field_length
,
120 if isinstance(tag
.printable
, six
.binary_type
):
121 # Force it to be decoded as UTF-8 so that it'll fit into the DB
122 data
['printable'] = tag
.printable
.decode('utf8', 'replace')
124 if type(tag
.values
) == list:
125 data
['values'] = [_ratio_to_list(val
) if isinstance(val
, Ratio
) else val
126 for val
in tag
.values
]
128 if isinstance(tag
.values
, six
.binary_type
):
129 # Force UTF-8, so that it fits into the DB
130 data
['values'] = tag
.values
.decode('utf8', 'replace')
132 data
['values'] = tag
.values
137 def _ratio_to_list(ratio
):
138 return [ratio
.num
, ratio
.den
]
141 def get_useful(tags
):
142 from collections
import OrderedDict
143 return OrderedDict((key
, tag
) for (key
, tag
) in six
.iteritems(tags
))
146 def get_gps_data(tags
):
148 Processes EXIF data returned by EXIF.py
150 def safe_gps_ratio_divide(ratio
):
153 return float(ratio
.num
) / float(ratio
.den
)
157 if not 'Image GPSInfo' in tags
:
162 'latitude': tags
['GPS GPSLatitude'],
163 'longitude': tags
['GPS GPSLongitude']}
165 for key
, dat
in six
.iteritems(dms_data
):
168 safe_gps_ratio_divide(v
[0]) \
169 + (safe_gps_ratio_divide(v
[1]) / 60) \
170 + (safe_gps_ratio_divide(v
[2]) / (60 * 60))
173 if tags
['GPS GPSLatitudeRef'].values
== 'S':
174 gps_data
['latitude'] /= -1
176 if tags
['GPS GPSLongitudeRef'].values
== 'W':
177 gps_data
['longitude'] /= -1
183 direction
= tags
['GPS GPSImgDirection'].values
[0]
184 gps_data
['direction'] = safe_gps_ratio_divide(direction
)
189 altitude
= tags
['GPS GPSAltitude'].values
[0]
190 gps_data
['altitude'] = safe_gps_ratio_divide(altitude
)