336 lines
11 KiB
Python
336 lines
11 KiB
Python
# Created By: Virgil Dupras
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# Created On: 2011-04-20
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# Copyright 2012 Hardcoded Software (http://www.hardcoded.net)
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#
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# This software is licensed under the "BSD" License as described in the "LICENSE" file,
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# which should be included with this package. The terms are also available at
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# http://www.hardcoded.net/licenses/bsd_license
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# Heavily based on http://topo.math.u-psud.fr/~bousch/exifdump.py by Thierry Bousch (Public Domain)
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import logging
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EXIF_TAGS = {
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0x0100: "ImageWidth",
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0x0101: "ImageLength",
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0x0102: "BitsPerSample",
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0x0103: "Compression",
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0x0106: "PhotometricInterpretation",
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0x010A: "FillOrder",
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0x010D: "DocumentName",
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0x010E: "ImageDescription",
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0x010F: "Make",
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0x0110: "Model",
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0x0111: "StripOffsets",
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0x0112: "Orientation",
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0x0115: "SamplesPerPixel",
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0x0116: "RowsPerStrip",
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0x0117: "StripByteCounts",
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0x011A: "XResolution",
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0x011B: "YResolution",
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0x011C: "PlanarConfiguration",
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0x0128: "ResolutionUnit",
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0x012D: "TransferFunction",
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0x0131: "Software",
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0x0132: "DateTime",
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0x013B: "Artist",
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0x013E: "WhitePoint",
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0x013F: "PrimaryChromaticities",
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0x0156: "TransferRange",
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0x0200: "JPEGProc",
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0x0201: "JPEGInterchangeFormat",
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0x0202: "JPEGInterchangeFormatLength",
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0x0211: "YCbCrCoefficients",
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0x0212: "YCbCrSubSampling",
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0x0213: "YCbCrPositioning",
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0x0214: "ReferenceBlackWhite",
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0x828F: "BatteryLevel",
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0x8298: "Copyright",
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0x829A: "ExposureTime",
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0x829D: "FNumber",
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0x83BB: "IPTC/NAA",
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0x8769: "ExifIFDPointer",
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0x8773: "InterColorProfile",
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0x8822: "ExposureProgram",
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0x8824: "SpectralSensitivity",
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0x8825: "GPSInfoIFDPointer",
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0x8827: "ISOSpeedRatings",
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0x8828: "OECF",
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0x9000: "ExifVersion",
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0x9003: "DateTimeOriginal",
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0x9004: "DateTimeDigitized",
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0x9101: "ComponentsConfiguration",
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0x9102: "CompressedBitsPerPixel",
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0x9201: "ShutterSpeedValue",
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0x9202: "ApertureValue",
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0x9203: "BrightnessValue",
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0x9204: "ExposureBiasValue",
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0x9205: "MaxApertureValue",
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0x9206: "SubjectDistance",
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0x9207: "MeteringMode",
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0x9208: "LightSource",
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0x9209: "Flash",
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0x920A: "FocalLength",
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0x9214: "SubjectArea",
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0x927C: "MakerNote",
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0x9286: "UserComment",
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0x9290: "SubSecTime",
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0x9291: "SubSecTimeOriginal",
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0x9292: "SubSecTimeDigitized",
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0xA000: "FlashPixVersion",
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0xA001: "ColorSpace",
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0xA002: "PixelXDimension",
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0xA003: "PixelYDimension",
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0xA004: "RelatedSoundFile",
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0xA005: "InteroperabilityIFDPointer",
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0xA20B: "FlashEnergy", # 0x920B in TIFF/EP
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0xA20C: "SpatialFrequencyResponse", # 0x920C - -
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0xA20E: "FocalPlaneXResolution", # 0x920E - -
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0xA20F: "FocalPlaneYResolution", # 0x920F - -
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0xA210: "FocalPlaneResolutionUnit", # 0x9210 - -
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0xA214: "SubjectLocation", # 0x9214 - -
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0xA215: "ExposureIndex", # 0x9215 - -
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0xA217: "SensingMethod", # 0x9217 - -
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0xA300: "FileSource",
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0xA301: "SceneType",
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0xA302: "CFAPattern", # 0x828E in TIFF/EP
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0xA401: "CustomRendered",
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0xA402: "ExposureMode",
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0xA403: "WhiteBalance",
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0xA404: "DigitalZoomRatio",
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0xA405: "FocalLengthIn35mmFilm",
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0xA406: "SceneCaptureType",
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0xA407: "GainControl",
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0xA408: "Contrast",
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0xA409: "Saturation",
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0xA40A: "Sharpness",
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0xA40B: "DeviceSettingDescription",
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0xA40C: "SubjectDistanceRange",
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0xA420: "ImageUniqueID",
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}
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INTR_TAGS = {
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0x0001: "InteroperabilityIndex",
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0x0002: "InteroperabilityVersion",
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0x1000: "RelatedImageFileFormat",
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0x1001: "RelatedImageWidth",
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0x1002: "RelatedImageLength",
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}
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GPS_TA0GS = {
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0x00: "GPSVersionID",
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0x01: "GPSLatitudeRef",
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0x02: "GPSLatitude",
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0x03: "GPSLongitudeRef",
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0x04: "GPSLongitude",
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0x05: "GPSAltitudeRef",
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0x06: "GPSAltitude",
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0x07: "GPSTimeStamp",
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0x08: "GPSSatellites",
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0x09: "GPSStatus",
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0x0A: "GPSMeasureMode",
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0x0B: "GPSDOP",
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0x0C: "GPSSpeedRef",
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0x0D: "GPSSpeed",
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0x0E: "GPSTrackRef",
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0x0F: "GPSTrack",
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0x10: "GPSImgDirectionRef",
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0x11: "GPSImgDirection",
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0x12: "GPSMapDatum",
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0x13: "GPSDestLatitudeRef",
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0x14: "GPSDestLatitude",
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0x15: "GPSDestLongitudeRef",
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0x16: "GPSDestLongitude",
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0x17: "GPSDestBearingRef",
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0x18: "GPSDestBearing",
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0x19: "GPSDestDistanceRef",
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0x1A: "GPSDestDistance",
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0x1B: "GPSProcessingMethod",
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0x1C: "GPSAreaInformation",
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0x1D: "GPSDateStamp",
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0x1E: "GPSDifferential"
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}
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INTEL_ENDIAN = ord('I')
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MOTOROLA_ENDIAN = ord('M')
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# About MAX_COUNT: It's possible to have corrupted exif tags where the entry count is way too high
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# and thus makes us loop, not endlessly, but for heck of a long time for nothing. Therefore, we put
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# an arbitrary limit on the entry count we'll allow ourselves to read and any IFD reporting more
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# entries than that will be considered corrupt.
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MAX_COUNT = 0xffff
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def s2n_motorola(bytes):
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x = 0
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for c in bytes:
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x = (x << 8) | c
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return x
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def s2n_intel(bytes):
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x = 0
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y = 0
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for c in bytes:
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x = x | (c << y)
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y = y + 8
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return x
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class Fraction:
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def __init__(self, num, den):
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self.num = num
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self.den = den
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def __repr__(self):
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return '%d/%d' % (self.num, self.den)
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class TIFF_file:
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def __init__(self, data):
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self.data = data
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self.endian = data[0]
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self.s2nfunc = s2n_intel if self.endian == INTEL_ENDIAN else s2n_motorola
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def s2n(self, offset, length, signed=0, debug=False):
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slice = self.data[offset:offset+length]
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val = self.s2nfunc(slice)
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# Sign extension ?
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if signed:
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msb = 1 << (8*length - 1)
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if val & msb:
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val = val - (msb << 1)
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if debug:
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logging.debug(self.endian)
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logging.debug("Slice for offset %d length %d: %r and value: %d", offset, length, slice, val)
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return val
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def first_IFD(self):
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return self.s2n(4, 4)
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def next_IFD(self, ifd):
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entries = self.s2n(ifd, 2)
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return self.s2n(ifd + 2 + 12 * entries, 4)
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def list_IFDs(self):
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i = self.first_IFD()
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a = []
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while i:
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a.append(i)
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i = self.next_IFD(i)
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return a
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def dump_IFD(self, ifd):
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entries = self.s2n(ifd, 2)
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logging.debug("Entries for IFD %d: %d", ifd, entries)
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if entries > MAX_COUNT:
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logging.debug("Probably corrupt. Aborting.")
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return []
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a = []
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for i in range(entries):
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entry = ifd + 2 + 12*i
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tag = self.s2n(entry, 2)
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type = self.s2n(entry+2, 2)
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if not 1 <= type <= 10:
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continue # not handled
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typelen = [ 1, 1, 2, 4, 8, 1, 1, 2, 4, 8 ] [type-1]
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count = self.s2n(entry+4, 4)
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if count > MAX_COUNT:
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logging.debug("Probably corrupt. Aborting.")
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return []
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offset = entry+8
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if count*typelen > 4:
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offset = self.s2n(offset, 4)
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if type == 2:
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# Special case: nul-terminated ASCII string
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values = str(self.data[offset:offset+count-1], encoding='latin-1')
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else:
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values = []
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signed = (type == 6 or type >= 8)
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for j in range(count):
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if type in {5, 10}:
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# The type is either 5 or 10
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value_j = Fraction(self.s2n(offset, 4, signed),
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self.s2n(offset+4, 4, signed))
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else:
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# Not a fraction
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value_j = self.s2n(offset, typelen, signed)
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values.append(value_j)
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offset = offset + typelen
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# Now "values" is either a string or an array
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a.append((tag,type,values))
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return a
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def read_exif_header(fp):
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# If `fp`'s first bytes are not exif, it tries to find it in the next 4kb
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def isexif(data):
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return data[0:4] == b'\377\330\377\341' and data[6:10] == b'Exif'
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data = fp.read(12)
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if isexif(data):
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return data
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# ok, not exif, try to find it
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large_data = fp.read(4096)
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try:
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index = large_data.index(b'Exif')
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data = large_data[index-6:index+6]
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# large_data omits the first 12 bytes, and the index is at the middle of the header, so we
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# must seek index + 18
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fp.seek(index+18)
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return data
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except ValueError:
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raise ValueError("Not an Exif file")
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def get_fields(fp):
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data = read_exif_header(fp)
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length = data[4] * 256 + data[5]
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logging.debug("Exif header length: %d bytes", length)
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data = fp.read(length-8)
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data_format = data[0]
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logging.debug("%s format", {INTEL_ENDIAN:'Intel', MOTOROLA_ENDIAN:'Motorola'}[data_format])
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T = TIFF_file(data)
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# There may be more than one IFD per file, but we only read the first one because others are
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# most likely thumbnails.
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main_IFD_offset = T.first_IFD()
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result = {}
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def add_tag_to_result(tag, values):
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try:
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stag = EXIF_TAGS[tag]
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except KeyError:
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stag = '0x%04X' % tag
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if stag in result:
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return # don't overwrite data
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result[stag] = values
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logging.debug("IFD at offset %d", main_IFD_offset)
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IFD = T.dump_IFD(main_IFD_offset)
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exif_off = gps_off = 0
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for tag, type, values in IFD:
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if tag == 0x8769:
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exif_off = values[0]
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continue
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if tag == 0x8825:
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gps_off = values[0]
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continue
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add_tag_to_result(tag, values)
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if exif_off:
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logging.debug("Exif SubIFD at offset %d:", exif_off)
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IFD = T.dump_IFD(exif_off)
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# Recent digital cameras have a little subdirectory
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# here, pointed to by tag 0xA005. Apparently, it's the
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# "Interoperability IFD", defined in Exif 2.1 and DCF.
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intr_off = 0
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for tag, type, values in IFD:
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if tag == 0xA005:
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intr_off = values[0]
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continue
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add_tag_to_result(tag, values)
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if intr_off:
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logging.debug("Exif Interoperability SubSubIFD at offset %d:", intr_off)
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IFD = T.dump_IFD(intr_off)
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for tag, type, values in IFD:
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add_tag_to_result(tag, values)
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if gps_off:
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logging.debug("GPS SubIFD at offset %d:", gps_off)
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IFD = T.dump_IFD(gps_off)
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for tag, type, values in IFD:
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add_tag_to_result(tag, values)
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return result
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