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dupeguru/core/pe/exif.py

347 lines
11 KiB
Python

# Created By: Virgil Dupras
# Created On: 2011-04-20
# Copyright 2015 Hardcoded Software (http://www.hardcoded.net)
#
# This software is licensed under the "GPLv3" License as described in the "LICENSE" file,
# which should be included with this package. The terms are also available at
# http://www.gnu.org/licenses/gpl-3.0.html
# 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):
data_slice = self.data[offset : offset + length]
val = self.s2nfunc(data_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,
data_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)
entry_type = self.s2n(entry + 2, 2)
if not 1 <= entry_type <= 10:
continue # not handled
typelen = [1, 1, 2, 4, 8, 1, 1, 2, 4, 8][entry_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 entry_type == 2:
# Special case: nul-terminated ASCII string
values = str(self.data[offset : offset + count - 1], encoding="latin-1")
else:
values = []
signed = entry_type == 6 or entry_type >= 8
for _ in range(count):
if entry_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, entry_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