# Created By: Virgil Dupras # Created On: 2011-04-20 # Copyright 2015 Hardcoded Software (http://www.hardcoded.net) # # This software is licensed under the "BSD" License as described in the "LICENSE" file, # which should be included with this package. The terms are also available at # http://www.hardcoded.net/licenses/bsd_license # Heavily based on http://topo.math.u-psud.fr/~bousch/exifdump.py by Thierry Bousch (Public Domain) import logging EXIF_TAGS = { 0x0100: "ImageWidth", 0x0101: "ImageLength", 0x0102: "BitsPerSample", 0x0103: "Compression", 0x0106: "PhotometricInterpretation", 0x010A: "FillOrder", 0x010D: "DocumentName", 0x010E: "ImageDescription", 0x010F: "Make", 0x0110: "Model", 0x0111: "StripOffsets", 0x0112: "Orientation", 0x0115: "SamplesPerPixel", 0x0116: "RowsPerStrip", 0x0117: "StripByteCounts", 0x011A: "XResolution", 0x011B: "YResolution", 0x011C: "PlanarConfiguration", 0x0128: "ResolutionUnit", 0x012D: "TransferFunction", 0x0131: "Software", 0x0132: "DateTime", 0x013B: "Artist", 0x013E: "WhitePoint", 0x013F: "PrimaryChromaticities", 0x0156: "TransferRange", 0x0200: "JPEGProc", 0x0201: "JPEGInterchangeFormat", 0x0202: "JPEGInterchangeFormatLength", 0x0211: "YCbCrCoefficients", 0x0212: "YCbCrSubSampling", 0x0213: "YCbCrPositioning", 0x0214: "ReferenceBlackWhite", 0x828F: "BatteryLevel", 0x8298: "Copyright", 0x829A: "ExposureTime", 0x829D: "FNumber", 0x83BB: "IPTC/NAA", 0x8769: "ExifIFDPointer", 0x8773: "InterColorProfile", 0x8822: "ExposureProgram", 0x8824: "SpectralSensitivity", 0x8825: "GPSInfoIFDPointer", 0x8827: "ISOSpeedRatings", 0x8828: "OECF", 0x9000: "ExifVersion", 0x9003: "DateTimeOriginal", 0x9004: "DateTimeDigitized", 0x9101: "ComponentsConfiguration", 0x9102: "CompressedBitsPerPixel", 0x9201: "ShutterSpeedValue", 0x9202: "ApertureValue", 0x9203: "BrightnessValue", 0x9204: "ExposureBiasValue", 0x9205: "MaxApertureValue", 0x9206: "SubjectDistance", 0x9207: "MeteringMode", 0x9208: "LightSource", 0x9209: "Flash", 0x920A: "FocalLength", 0x9214: "SubjectArea", 0x927C: "MakerNote", 0x9286: "UserComment", 0x9290: "SubSecTime", 0x9291: "SubSecTimeOriginal", 0x9292: "SubSecTimeDigitized", 0xA000: "FlashPixVersion", 0xA001: "ColorSpace", 0xA002: "PixelXDimension", 0xA003: "PixelYDimension", 0xA004: "RelatedSoundFile", 0xA005: "InteroperabilityIFDPointer", 0xA20B: "FlashEnergy", # 0x920B in TIFF/EP 0xA20C: "SpatialFrequencyResponse", # 0x920C - - 0xA20E: "FocalPlaneXResolution", # 0x920E - - 0xA20F: "FocalPlaneYResolution", # 0x920F - - 0xA210: "FocalPlaneResolutionUnit", # 0x9210 - - 0xA214: "SubjectLocation", # 0x9214 - - 0xA215: "ExposureIndex", # 0x9215 - - 0xA217: "SensingMethod", # 0x9217 - - 0xA300: "FileSource", 0xA301: "SceneType", 0xA302: "CFAPattern", # 0x828E in TIFF/EP 0xA401: "CustomRendered", 0xA402: "ExposureMode", 0xA403: "WhiteBalance", 0xA404: "DigitalZoomRatio", 0xA405: "FocalLengthIn35mmFilm", 0xA406: "SceneCaptureType", 0xA407: "GainControl", 0xA408: "Contrast", 0xA409: "Saturation", 0xA40A: "Sharpness", 0xA40B: "DeviceSettingDescription", 0xA40C: "SubjectDistanceRange", 0xA420: "ImageUniqueID", } INTR_TAGS = { 0x0001: "InteroperabilityIndex", 0x0002: "InteroperabilityVersion", 0x1000: "RelatedImageFileFormat", 0x1001: "RelatedImageWidth", 0x1002: "RelatedImageLength", } GPS_TA0GS = { 0x00: "GPSVersionID", 0x01: "GPSLatitudeRef", 0x02: "GPSLatitude", 0x03: "GPSLongitudeRef", 0x04: "GPSLongitude", 0x05: "GPSAltitudeRef", 0x06: "GPSAltitude", 0x07: "GPSTimeStamp", 0x08: "GPSSatellites", 0x09: "GPSStatus", 0x0A: "GPSMeasureMode", 0x0B: "GPSDOP", 0x0C: "GPSSpeedRef", 0x0D: "GPSSpeed", 0x0E: "GPSTrackRef", 0x0F: "GPSTrack", 0x10: "GPSImgDirectionRef", 0x11: "GPSImgDirection", 0x12: "GPSMapDatum", 0x13: "GPSDestLatitudeRef", 0x14: "GPSDestLatitude", 0x15: "GPSDestLongitudeRef", 0x16: "GPSDestLongitude", 0x17: "GPSDestBearingRef", 0x18: "GPSDestBearing", 0x19: "GPSDestDistanceRef", 0x1A: "GPSDestDistance", 0x1B: "GPSProcessingMethod", 0x1C: "GPSAreaInformation", 0x1D: "GPSDateStamp", 0x1E: "GPSDifferential" } INTEL_ENDIAN = ord('I') MOTOROLA_ENDIAN = ord('M') # About MAX_COUNT: It's possible to have corrupted exif tags where the entry count is way too high # and thus makes us loop, not endlessly, but for heck of a long time for nothing. Therefore, we put # an arbitrary limit on the entry count we'll allow ourselves to read and any IFD reporting more # entries than that will be considered corrupt. MAX_COUNT = 0xffff def s2n_motorola(bytes): x = 0 for c in bytes: x = (x << 8) | c return x def s2n_intel(bytes): x = 0 y = 0 for c in bytes: x = x | (c << y) y = y + 8 return x class Fraction: def __init__(self, num, den): self.num = num self.den = den def __repr__(self): return '%d/%d' % (self.num, self.den) class TIFF_file: def __init__(self, data): self.data = data self.endian = data[0] self.s2nfunc = s2n_intel if self.endian == INTEL_ENDIAN else s2n_motorola def s2n(self, offset, length, signed=0, debug=False): slice = self.data[offset:offset+length] val = self.s2nfunc(slice) # Sign extension ? if signed: msb = 1 << (8*length - 1) if val & msb: val = val - (msb << 1) if debug: logging.debug(self.endian) logging.debug("Slice for offset %d length %d: %r and value: %d", offset, length, slice, val) return val def first_IFD(self): return self.s2n(4, 4) def next_IFD(self, ifd): entries = self.s2n(ifd, 2) return self.s2n(ifd + 2 + 12 * entries, 4) def list_IFDs(self): i = self.first_IFD() a = [] while i: a.append(i) i = self.next_IFD(i) return a def dump_IFD(self, ifd): entries = self.s2n(ifd, 2) logging.debug("Entries for IFD %d: %d", ifd, entries) if entries > MAX_COUNT: logging.debug("Probably corrupt. Aborting.") return [] a = [] for i in range(entries): entry = ifd + 2 + 12*i tag = self.s2n(entry, 2) type = self.s2n(entry+2, 2) if not 1 <= type <= 10: continue # not handled typelen = [1, 1, 2, 4, 8, 1, 1, 2, 4, 8][type-1] count = self.s2n(entry+4, 4) if count > MAX_COUNT: logging.debug("Probably corrupt. Aborting.") return [] offset = entry+8 if count*typelen > 4: offset = self.s2n(offset, 4) if type == 2: # Special case: nul-terminated ASCII string values = str(self.data[offset:offset+count-1], encoding='latin-1') else: values = [] signed = (type == 6 or type >= 8) for j in range(count): if type in {5, 10}: # The type is either 5 or 10 value_j = Fraction(self.s2n(offset, 4, signed), self.s2n(offset+4, 4, signed)) else: # Not a fraction value_j = self.s2n(offset, typelen, signed) values.append(value_j) offset = offset + typelen # Now "values" is either a string or an array a.append((tag, type, values)) return a def read_exif_header(fp): # If `fp`'s first bytes are not exif, it tries to find it in the next 4kb def isexif(data): return data[0:4] == b'\377\330\377\341' and data[6:10] == b'Exif' data = fp.read(12) if isexif(data): return data # ok, not exif, try to find it large_data = fp.read(4096) try: index = large_data.index(b'Exif') data = large_data[index-6:index+6] # large_data omits the first 12 bytes, and the index is at the middle of the header, so we # must seek index + 18 fp.seek(index+18) return data except ValueError: raise ValueError("Not an Exif file") def get_fields(fp): data = read_exif_header(fp) length = data[4] * 256 + data[5] logging.debug("Exif header length: %d bytes", length) data = fp.read(length-8) data_format = data[0] logging.debug("%s format", {INTEL_ENDIAN: 'Intel', MOTOROLA_ENDIAN: 'Motorola'}[data_format]) T = TIFF_file(data) # There may be more than one IFD per file, but we only read the first one because others are # most likely thumbnails. main_IFD_offset = T.first_IFD() result = {} def add_tag_to_result(tag, values): try: stag = EXIF_TAGS[tag] except KeyError: stag = '0x%04X' % tag if stag in result: return # don't overwrite data result[stag] = values logging.debug("IFD at offset %d", main_IFD_offset) IFD = T.dump_IFD(main_IFD_offset) exif_off = gps_off = 0 for tag, type, values in IFD: if tag == 0x8769: exif_off = values[0] continue if tag == 0x8825: gps_off = values[0] continue add_tag_to_result(tag, values) if exif_off: logging.debug("Exif SubIFD at offset %d:", exif_off) IFD = T.dump_IFD(exif_off) # Recent digital cameras have a little subdirectory # here, pointed to by tag 0xA005. Apparently, it's the # "Interoperability IFD", defined in Exif 2.1 and DCF. intr_off = 0 for tag, type, values in IFD: if tag == 0xA005: intr_off = values[0] continue add_tag_to_result(tag, values) if intr_off: logging.debug("Exif Interoperability SubSubIFD at offset %d:", intr_off) IFD = T.dump_IFD(intr_off) for tag, type, values in IFD: add_tag_to_result(tag, values) if gps_off: logging.debug("GPS SubIFD at offset %d:", gps_off) IFD = T.dump_IFD(gps_off) for tag, type, values in IFD: add_tag_to_result(tag, values) return result