Added Exif classes for preliminary Exif image, photo, iop, gps support.
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jevans
parent
0f20fc18af
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fd2fd63b28
1 changed files with 227 additions and 68 deletions
295
glymur/jp2box.py
295
glymur/jp2box.py
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@ -1619,12 +1619,238 @@ class UUIDBox(Jp2kBox):
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text = buffer.decode('utf-8')
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kwargs['data'] = ET.fromstring(text)
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elif kwargs['uuid'].bytes == b'JpgTiffExif->JP2':
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kwargs['data'] = _parse_exif(buffer)
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kwargs['data'] = Exif(buffer).exif_image
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else:
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kwargs['data'] = buffer
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box = UUIDBox(**kwargs)
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return box
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class Exif:
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"""
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Attributes
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----------
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buffer : bytes
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Raw byte stream consisting of the UUID data.
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endian : str
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Either '<' for big-endian, or '>' for little-endian.
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"""
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def __init__(self, buffer):
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"""Interpret raw buffer consisting of Exif IFD.
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"""
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self.exif_image = None
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self.exif_photo = None
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self.exif_gpsinfo = None
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self.exif_iop = None
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self.buffer = buffer
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# Ignore the first six bytes.
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# Next 8 should be (73, 73, 42, 8)
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data = struct.unpack('<BBHI', buffer[6:14])
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if data[0] == 73 and data[1] == 73:
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# little endian
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self.endian = '<'
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else:
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# big endian
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self.endian = '>'
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offset = data[3]
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# This is the 'Exif Image' portion.
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exif = ExifImageIfd(self.endian, buffer[6:], offset)
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self.exif_image = exif.ifd
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if 'ExifTag' in self.exif_image.keys():
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offset = self.exif_image['ExifTag']
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photo = ExifPhotoIfd(self.endian, buffer[6:], offset)
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self.exif_photo = photo.ifd
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if 'InteroperabilityTag' in self.exif_photo.keys():
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offset = self.exif_photo['InteroperabilityTag']
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interop = ExifInteroperabilityIfd(self.endian,
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buffer[6:],
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offset)
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self.iop = interop.ifd
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if 'GPSTag' in self.exif_image.keys():
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offset = self.exif_image['GPSTag']
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gps = ExifGPSInfoIfd(self.endian, buffer[6:], offset)
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self.exif_gpsinfo = gps.ifd
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class Ifd:
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"""
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Attributes
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----------
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buffer : bytes
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Raw byte stream consisting of the UUID data.
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datatype2fmt : dictionary
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Class attribute, maps the TIFF enumerated datatype to the python
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datatype and data width.
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endian : str
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Either '<' for big-endian, or '>' for little-endian.
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num_tags : int
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Number of tags in the IFD.
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raw_ifd : dictionary
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Maps tag number to "mildly-interpreted" tag value.
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"""
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datatype2fmt = {1: ('B', 1),
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2: ('B', 1),
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3: ('H', 2),
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4: ('I', 4),
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5: ('II', 8),
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7: ('B', 1),
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9: ('i', 4),
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10: ('ii', 8)}
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def __init__(self, endian, buffer, offset):
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self.endian = endian
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self.buffer = buffer
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self.num_tags, = struct.unpack(endian + 'H', buffer[offset:offset + 2])
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fmt = self.endian + 'HHII' * self.num_tags
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data = struct.unpack(fmt, buffer[offset + 2:offset + 2 + self.num_tags * 12])
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self.raw_ifd = {}
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for j, tag in enumerate(data[0::4]):
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tag_entry = buffer[offset + 2 + j * 12 + 8:offset + 2 + j * 12 + 8 + 4]
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payload = self.parse_tag(data[j * 4 + 1],
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data[j * 4 + 2],
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tag_entry)
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self.raw_ifd[tag] = payload
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def parse_tag(self, dtype, count, offset_buf):
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"""Interpret an Exif image tag data payload.
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"""
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fmt = self.datatype2fmt[dtype][0] * count
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payload_size = self.datatype2fmt[dtype][1] * count
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if payload_size <= 4:
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# Interpret the payload from the 4 bytes in the tag entry.
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target_buffer = offset_buf[:payload_size]
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else:
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# Interpret the payload at the offset specified by the 4 bytes in the
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# tag entry.
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offset, = struct.unpack(self.endian + 'I', offset_buf)
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target_buffer = self.buffer[offset:offset + payload_size]
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if dtype == 2:
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# ASCII
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payload = target_buffer.decode('utf-8').rstrip()
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else:
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payload = struct.unpack(self.endian + fmt, target_buffer)
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if dtype == 5 or dtype == 10:
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# Rational or Signed Rational. Construct the list of values.
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rational_payload = []
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for j in range(count):
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value = float(payload[j * 2]) / float(payload[j * 2 + 1])
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rational_payload.append(value)
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payload = rational_payload
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if count == 1:
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# If just a single value, then return a scalar instead of a
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# tuple.
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payload = payload[0]
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return payload
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class ExifImageIfd(Ifd):
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tagnum2name = {271: 'Make',
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272: 'Model',
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282: 'XResolution',
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283: 'YResolution',
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296: 'ResolutionUnit',
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531: 'YCbCrPositioning',
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34665: 'ExifTag',
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34853: 'GPSTag'}
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def __init__(self, endian, buffer, offset):
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Ifd.__init__(self, endian, buffer, offset)
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# Now post process the raw IFD.
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self.ifd = {}
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for tag, value in self.raw_ifd.items():
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tag_name = self.tagnum2name[tag]
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self.ifd[tag_name] = value
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class ExifPhotoIfd(Ifd):
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tagnum2name = {34855: 'ISOSpeedRatings',
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36864: 'ExifVersion',
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36867: 'DateTimeOriginal',
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36868: 'DateTimeDigitized',
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37121: 'ComponentsConfiguration',
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37386: 'FocalLength',
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40960: 'FlashpixVersion',
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40961: 'ColorSpace',
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40962: 'PixelXDimension',
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40963: 'PixelYDimension',
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40965: 'InteroperabilityTag'}
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def __init__(self, endian, buffer, offset):
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Ifd.__init__(self, endian, buffer, offset)
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# Now post process the raw IFD.
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self.ifd = {}
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for tag, value in self.raw_ifd.items():
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tag_name = self.tagnum2name[tag]
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self.ifd[tag_name] = value
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class ExifGPSInfoIfd(Ifd):
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tagnum2name = {0: 'GPSVersionID',
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1: 'GPSLatitudeRef',
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2: 'GPSLatitude',
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3: 'GPSLongitudeRef',
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4: 'GPSLongitude',
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5: 'GPSAltitudeRef',
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6: 'GPSAltitude',
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7: 'GPSTimeStamp',
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8: 'GPSSatellites',
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9: 'GPSStatus',
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10: 'GPSMeasureMode',
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11: 'GPSDOP',
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12: 'GPSSpeedRef',
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13: 'GPSSpeed',
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14: 'GPSTrackRef',
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15: 'GPSTrack',
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16: 'GPSImgDirectionRef',
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17: 'GPSImgDirection',
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18: 'GPSMapDatum',
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19: 'GPSDestLatitudeRef',
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20: 'GPSDestLatitude',
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21: 'GPSDestLongitudeRef',
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22: 'GPSDestLongitude',
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23: 'GPSDestBearingRef',
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24: 'GPSDestBearing',
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25: 'GPSDestDistanceRef',
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26: 'GPSDestDistance',
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27: 'GPSProcessingMethod',
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28: 'GPSAreaInformation',
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29: 'GPSDateStamp',
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30: 'GPSDifferential'}
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def __init__(self, endian, buffer, offset):
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Ifd.__init__(self, endian, buffer, offset)
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# Now post process the raw IFD.
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self.ifd = {}
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for tag, value in self.raw_ifd.items():
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tag_name = self.tagnum2name[tag]
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self.ifd[tag_name] = value
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class ExifInteroperabilityIfd(Ifd):
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tagnum2name = {1: 'InteroperabilityIndex',
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2: 'InteroperabilityVersion',
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4096: 'RelatedImageFileFormat',
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4097: 'RelatedImageWidth',
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4098: 'RelatedImageLength'}
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def __init__(self, endian, buffer, offset):
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Ifd.__init__(self, endian, buffer, offset)
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# Now post process the raw IFD.
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self.ifd = {}
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for tag, value in self.raw_ifd.items():
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tag_name = self.tagnum2name[tag]
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self.ifd[tag_name] = value
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# Map each box ID to the corresponding class.
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_box_with_id = {
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@ -1668,73 +1894,6 @@ def _indent(elem, level=0):
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if level and (not elem.tail or not elem.tail.strip()):
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elem.tail = i
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_tagnum2name = {271: 'Make', 272: 'Model',
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282: 'XResolution', 283: 'YResolution',
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296: 'ResolutionUnit',
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531: 'YCbCrPositioning',
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34665: 'ExifTag',
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34853: 'GPSTag'}
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def _parse_exif(buffer):
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"""Interpret raw buffer consisting of Exif IFD.
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"""
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# Ignore the first six bytes.
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# Next six should be (73, 73, 42, 8, numtags)
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data = struct.unpack('<BBHIH', buffer[6:16])
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num_tags = data[4]
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fmt = '<' + 'HHII' * num_tags
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data = struct.unpack(fmt, buffer[16:16 + num_tags * 12])
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exif = {}
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for j, tag in enumerate(data[0::4]):
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offset_bytes = buffer[16 + j * 12 + 8:16 + j * 12 + 8 + 4]
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exif[_tagnum2name[tag]] = _parse_exif_image_tag(data[j * 4 + 1],
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data[j * 4 + 2],
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offset_bytes,
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buffer)
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print(exif)
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return exif
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# Map the TIFF enumerated datatype to the python datatype and data width.
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_datatype2fmt = {1: ('B', 1),
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2: ('B', 1),
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3: ('H', 2),
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4: ('I', 4),
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5: ('II', 8),
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7: ('B', 1),
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9: ('i', 4),
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10: ('ii', 8)}
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def _parse_exif_image_tag(datatype, count, offset_buffer, exif_buffer):
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"""Interpret an Exif image tag data payload.
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"""
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fmt = _datatype2fmt[datatype][0] * count
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payload_size = _datatype2fmt[datatype][1] * count
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if payload_size <= 4:
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# Interpret the payload from the 4 bytes in the tag entry.
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target_buffer = offset_buffer[:payload_size]
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else:
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# Interpret the payload at the offset specified by the 4 bytes in the
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# tag entry.
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offset, = struct.unpack('<I', offset_buffer)
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target_buffer = exif_buffer[6 + offset:6 + offset + payload_size]
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if datatype == 2:
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payload = target_buffer.decode('utf-8').rstrip()
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else:
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payload = struct.unpack('<' + fmt, target_buffer)
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if datatype == 5:
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rational_payload = []
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for j in range(count):
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value = float(payload[j * 2]) / float(payload[j * 2 + 1])
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rational_payload.append(value)
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payload = rational_payload
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if count == 1:
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payload = payload[0]
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return payload
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def _pretty_print_xml(xml, level=0):
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"""Pretty print XML data.
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"""
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