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Pillow/PIL/JpegImagePlugin.py
Eric W. Brown 53b7f6294b First steps toward MPO support. 
Allows Pillow to distinguish between JPEGs and MPOs, and provides some
MPO metadata handling. Does not yet handle multiple frames.
2014-07-16 11:36:56 -04:00

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#
# The Python Imaging Library.
# $Id$
#
# JPEG (JFIF) file handling
#
# See "Digital Compression and Coding of Continous-Tone Still Images,
# Part 1, Requirements and Guidelines" (CCITT T.81 / ISO 10918-1)
#
# History:
# 1995-09-09 fl Created
# 1995-09-13 fl Added full parser
# 1996-03-25 fl Added hack to use the IJG command line utilities
# 1996-05-05 fl Workaround Photoshop 2.5 CMYK polarity bug
# 1996-05-28 fl Added draft support, JFIF version (0.1)
# 1996-12-30 fl Added encoder options, added progression property (0.2)
# 1997-08-27 fl Save mode 1 images as BW (0.3)
# 1998-07-12 fl Added YCbCr to draft and save methods (0.4)
# 1998-10-19 fl Don't hang on files using 16-bit DQT's (0.4.1)
# 2001-04-16 fl Extract DPI settings from JFIF files (0.4.2)
# 2002-07-01 fl Skip pad bytes before markers; identify Exif files (0.4.3)
# 2003-04-25 fl Added experimental EXIF decoder (0.5)
# 2003-06-06 fl Added experimental EXIF GPSinfo decoder
# 2003-09-13 fl Extract COM markers
# 2009-09-06 fl Added icc_profile support (from Florian Hoech)
# 2009-03-06 fl Changed CMYK handling; always use Adobe polarity (0.6)
# 2009-03-08 fl Added subsampling support (from Justin Huff).
#
# Copyright (c) 1997-2003 by Secret Labs AB.
# Copyright (c) 1995-1996 by Fredrik Lundh.
#
# See the README file for information on usage and redistribution.
#
__version__ = "0.6"
import array
import struct
import io
from PIL import Image, ImageFile, TiffImagePlugin, _binary
from PIL.JpegPresets import presets
from PIL._util import isStringType
i8 = _binary.i8
o8 = _binary.o8
i16 = _binary.i16be
i32 = _binary.i32be
#
# Parser
def Skip(self, marker):
n = i16(self.fp.read(2))-2
ImageFile._safe_read(self.fp, n)
def APP(self, marker):
#
# Application marker. Store these in the APP dictionary.
# Also look for well-known application markers.
n = i16(self.fp.read(2))-2
s = ImageFile._safe_read(self.fp, n)
app = "APP%d" % (marker & 15)
self.app[app] = s # compatibility
self.applist.append((app, s))
if marker == 0xFFE0 and s[:4] == b"JFIF":
# extract JFIF information
self.info["jfif"] = version = i16(s, 5) # version
self.info["jfif_version"] = divmod(version, 256)
# extract JFIF properties
try:
jfif_unit = i8(s[7])
jfif_density = i16(s, 8), i16(s, 10)
except:
pass
else:
if jfif_unit == 1:
self.info["dpi"] = jfif_density
self.info["jfif_unit"] = jfif_unit
self.info["jfif_density"] = jfif_density
elif marker == 0xFFE1 and s[:5] == b"Exif\0":
# extract Exif information (incomplete)
self.info["exif"] = s # FIXME: value will change
elif marker == 0xFFE2 and s[:5] == b"FPXR\0":
# extract FlashPix information (incomplete)
self.info["flashpix"] = s # FIXME: value will change
elif marker == 0xFFE2 and s[:12] == b"ICC_PROFILE\0":
# Since an ICC profile can be larger than the maximum size of
# a JPEG marker (64K), we need provisions to split it into
# multiple markers. The format defined by the ICC specifies
# one or more APP2 markers containing the following data:
# Identifying string ASCII "ICC_PROFILE\0" (12 bytes)
# Marker sequence number 1, 2, etc (1 byte)
# Number of markers Total of APP2's used (1 byte)
# Profile data (remainder of APP2 data)
# Decoders should use the marker sequence numbers to
# reassemble the profile, rather than assuming that the APP2
# markers appear in the correct sequence.
self.icclist.append(s)
elif marker == 0xFFEE and s[:5] == b"Adobe":
self.info["adobe"] = i16(s, 5)
# extract Adobe custom properties
try:
adobe_transform = i8(s[1])
except:
pass
else:
self.info["adobe_transform"] = adobe_transform
elif marker == 0xFFE2 and s[:4] == b"MPF\0":
# extract MPO information
self.info["mp"] = s[4:]
def COM(self, marker):
#
# Comment marker. Store these in the APP dictionary.
n = i16(self.fp.read(2))-2
s = ImageFile._safe_read(self.fp, n)
self.app["COM"] = s # compatibility
self.applist.append(("COM", s))
def SOF(self, marker):
#
# Start of frame marker. Defines the size and mode of the
# image. JPEG is colour blind, so we use some simple
# heuristics to map the number of layers to an appropriate
# mode. Note that this could be made a bit brighter, by
# looking for JFIF and Adobe APP markers.
n = i16(self.fp.read(2))-2
s = ImageFile._safe_read(self.fp, n)
self.size = i16(s[3:]), i16(s[1:])
self.bits = i8(s[0])
if self.bits != 8:
raise SyntaxError("cannot handle %d-bit layers" % self.bits)
self.layers = i8(s[5])
if self.layers == 1:
self.mode = "L"
elif self.layers == 3:
self.mode = "RGB"
elif self.layers == 4:
self.mode = "CMYK"
else:
raise SyntaxError("cannot handle %d-layer images" % self.layers)
if marker in [0xFFC2, 0xFFC6, 0xFFCA, 0xFFCE]:
self.info["progressive"] = self.info["progression"] = 1
if self.icclist:
# fixup icc profile
self.icclist.sort() # sort by sequence number
if i8(self.icclist[0][13]) == len(self.icclist):
profile = []
for p in self.icclist:
profile.append(p[14:])
icc_profile = b"".join(profile)
else:
icc_profile = None # wrong number of fragments
self.info["icc_profile"] = icc_profile
self.icclist = None
for i in range(6, len(s), 3):
t = s[i:i+3]
# 4-tuples: id, vsamp, hsamp, qtable
self.layer.append((t[0], i8(t[1])//16, i8(t[1]) & 15, i8(t[2])))
def DQT(self, marker):
#
# Define quantization table. Support baseline 8-bit tables
# only. Note that there might be more than one table in
# each marker.
# FIXME: The quantization tables can be used to estimate the
# compression quality.
n = i16(self.fp.read(2))-2
s = ImageFile._safe_read(self.fp, n)
while len(s):
if len(s) < 65:
raise SyntaxError("bad quantization table marker")
v = i8(s[0])
if v//16 == 0:
self.quantization[v & 15] = array.array("b", s[1:65])
s = s[65:]
else:
return # FIXME: add code to read 16-bit tables!
# raise SyntaxError, "bad quantization table element size"
#
# JPEG marker table
MARKER = {
0xFFC0: ("SOF0", "Baseline DCT", SOF),
0xFFC1: ("SOF1", "Extended Sequential DCT", SOF),
0xFFC2: ("SOF2", "Progressive DCT", SOF),
0xFFC3: ("SOF3", "Spatial lossless", SOF),
0xFFC4: ("DHT", "Define Huffman table", Skip),
0xFFC5: ("SOF5", "Differential sequential DCT", SOF),
0xFFC6: ("SOF6", "Differential progressive DCT", SOF),
0xFFC7: ("SOF7", "Differential spatial", SOF),
0xFFC8: ("JPG", "Extension", None),
0xFFC9: ("SOF9", "Extended sequential DCT (AC)", SOF),
0xFFCA: ("SOF10", "Progressive DCT (AC)", SOF),
0xFFCB: ("SOF11", "Spatial lossless DCT (AC)", SOF),
0xFFCC: ("DAC", "Define arithmetic coding conditioning", Skip),
0xFFCD: ("SOF13", "Differential sequential DCT (AC)", SOF),
0xFFCE: ("SOF14", "Differential progressive DCT (AC)", SOF),
0xFFCF: ("SOF15", "Differential spatial (AC)", SOF),
0xFFD0: ("RST0", "Restart 0", None),
0xFFD1: ("RST1", "Restart 1", None),
0xFFD2: ("RST2", "Restart 2", None),
0xFFD3: ("RST3", "Restart 3", None),
0xFFD4: ("RST4", "Restart 4", None),
0xFFD5: ("RST5", "Restart 5", None),
0xFFD6: ("RST6", "Restart 6", None),
0xFFD7: ("RST7", "Restart 7", None),
0xFFD8: ("SOI", "Start of image", None),
0xFFD9: ("EOI", "End of image", None),
0xFFDA: ("SOS", "Start of scan", Skip),
0xFFDB: ("DQT", "Define quantization table", DQT),
0xFFDC: ("DNL", "Define number of lines", Skip),
0xFFDD: ("DRI", "Define restart interval", Skip),
0xFFDE: ("DHP", "Define hierarchical progression", SOF),
0xFFDF: ("EXP", "Expand reference component", Skip),
0xFFE0: ("APP0", "Application segment 0", APP),
0xFFE1: ("APP1", "Application segment 1", APP),
0xFFE2: ("APP2", "Application segment 2", APP),
0xFFE3: ("APP3", "Application segment 3", APP),
0xFFE4: ("APP4", "Application segment 4", APP),
0xFFE5: ("APP5", "Application segment 5", APP),
0xFFE6: ("APP6", "Application segment 6", APP),
0xFFE7: ("APP7", "Application segment 7", APP),
0xFFE8: ("APP8", "Application segment 8", APP),
0xFFE9: ("APP9", "Application segment 9", APP),
0xFFEA: ("APP10", "Application segment 10", APP),
0xFFEB: ("APP11", "Application segment 11", APP),
0xFFEC: ("APP12", "Application segment 12", APP),
0xFFED: ("APP13", "Application segment 13", APP),
0xFFEE: ("APP14", "Application segment 14", APP),
0xFFEF: ("APP15", "Application segment 15", APP),
0xFFF0: ("JPG0", "Extension 0", None),
0xFFF1: ("JPG1", "Extension 1", None),
0xFFF2: ("JPG2", "Extension 2", None),
0xFFF3: ("JPG3", "Extension 3", None),
0xFFF4: ("JPG4", "Extension 4", None),
0xFFF5: ("JPG5", "Extension 5", None),
0xFFF6: ("JPG6", "Extension 6", None),
0xFFF7: ("JPG7", "Extension 7", None),
0xFFF8: ("JPG8", "Extension 8", None),
0xFFF9: ("JPG9", "Extension 9", None),
0xFFFA: ("JPG10", "Extension 10", None),
0xFFFB: ("JPG11", "Extension 11", None),
0xFFFC: ("JPG12", "Extension 12", None),
0xFFFD: ("JPG13", "Extension 13", None),
0xFFFE: ("COM", "Comment", COM)
}
def _accept(prefix):
return prefix[0:1] == b"\377"
##
# Image plugin for JPEG and JFIF images.
class JpegImageFile(ImageFile.ImageFile):
format = "JPEG"
format_description = "JPEG (ISO 10918)"
def _open(self):
s = self.fp.read(1)
if i8(s[0]) != 255:
raise SyntaxError("not a JPEG file")
# Create attributes
self.bits = self.layers = 0
# JPEG specifics (internal)
self.layer = []
self.huffman_dc = {}
self.huffman_ac = {}
self.quantization = {}
self.app = {} # compatibility
self.applist = []
self.icclist = []
while True:
i = i8(s)
if i == 0xFF:
s = s + self.fp.read(1)
i = i16(s)
else:
# Skip non-0xFF junk
s = b"\xff"
continue
if i in MARKER:
name, description, handler = MARKER[i]
# print hex(i), name, description
if handler is not None:
handler(self, i)
if i == 0xFFDA: # start of scan
rawmode = self.mode
if self.mode == "CMYK":
rawmode = "CMYK;I" # assume adobe conventions
self.tile = [("jpeg", (0, 0) + self.size, 0, (rawmode, ""))]
# self.__offset = self.fp.tell()
break
s = self.fp.read(1)
elif i == 0 or i == 0xFFFF:
# padded marker or junk; move on
s = b"\xff"
else:
raise SyntaxError("no marker found")
def draft(self, mode, size):
if len(self.tile) != 1:
return
d, e, o, a = self.tile[0]
scale = 0
if a[0] == "RGB" and mode in ["L", "YCbCr"]:
self.mode = mode
a = mode, ""
if size:
scale = max(self.size[0] // size[0], self.size[1] // size[1])
for s in [8, 4, 2, 1]:
if scale >= s:
break
e = e[0], e[1], (e[2]-e[0]+s-1)//s+e[0], (e[3]-e[1]+s-1)//s+e[1]
self.size = ((self.size[0]+s-1)//s, (self.size[1]+s-1)//s)
scale = s
self.tile = [(d, e, o, a)]
self.decoderconfig = (scale, 1)
return self
def load_djpeg(self):
# ALTERNATIVE: handle JPEGs via the IJG command line utilities
import subprocess
import tempfile
import os
f, path = tempfile.mkstemp()
os.close(f)
if os.path.exists(self.filename):
subprocess.check_call(["djpeg", "-outfile", path, self.filename])
else:
raise ValueError("Invalid Filename")
try:
self.im = Image.core.open_ppm(path)
finally:
try:
os.unlink(path)
except:
pass
self.mode = self.im.mode
self.size = self.im.size
self.tile = []
def _getexif(self):
return _getexif(self)
def _getmp(self):
return _getmp(self)
def _fixup(value):
# Helper function for _getexif() and _getmp()
if len(value) == 1:
return value[0]
return value
def _getexif(self):
# Extract EXIF information. This method is highly experimental,
# and is likely to be replaced with something better in a future
# version.
# The EXIF record consists of a TIFF file embedded in a JPEG
# application marker (!).
try:
data = self.info["exif"]
except KeyError:
return None
file = io.BytesIO(data[6:])
head = file.read(8)
exif = {}
# process dictionary
info = TiffImagePlugin.ImageFileDirectory(head)
info.load(file)
for key, value in info.items():
exif[key] = _fixup(value)
# get exif extension
try:
file.seek(exif[0x8769])
except KeyError:
pass
else:
info = TiffImagePlugin.ImageFileDirectory(head)
info.load(file)
for key, value in info.items():
exif[key] = _fixup(value)
# get gpsinfo extension
try:
file.seek(exif[0x8825])
except KeyError:
pass
else:
info = TiffImagePlugin.ImageFileDirectory(head)
info.load(file)
exif[0x8825] = gps = {}
for key, value in info.items():
gps[key] = _fixup(value)
return exif
def _getmp(self):
# Extract MP information. This method was inspired by the "highly
# experimental" _getexif version that's been in use for years now,
# itself based on the ImageFileDirectory class in the TIFF plug-in.
# The MP record essentially consists of a TIFF file embedded in a JPEG
# application marker.
try:
data = self.info["mp"]
except KeyError:
return None
file = io.BytesIO(data)
head = file.read(8)
mp = {}
# process dictionary
info = TiffImagePlugin.ImageFileDirectory(head)
info.load(file)
for key, value in info.items():
mp[key] = _fixup(value)
return mp
# --------------------------------------------------------------------
# stuff to save JPEG files
RAWMODE = {
"1": "L",
"L": "L",
"RGB": "RGB",
"RGBA": "RGB",
"RGBX": "RGB",
"CMYK": "CMYK;I", # assume adobe conventions
"YCbCr": "YCbCr",
}
zigzag_index = ( 0, 1, 5, 6, 14, 15, 27, 28,
2, 4, 7, 13, 16, 26, 29, 42,
3, 8, 12, 17, 25, 30, 41, 43,
9, 11, 18, 24, 31, 40, 44, 53,
10, 19, 23, 32, 39, 45, 52, 54,
20, 22, 33, 38, 46, 51, 55, 60,
21, 34, 37, 47, 50, 56, 59, 61,
35, 36, 48, 49, 57, 58, 62, 63)
samplings = {
(1, 1, 1, 1, 1, 1): 0,
(2, 1, 1, 1, 1, 1): 1,
(2, 2, 1, 1, 1, 1): 2,
}
def convert_dict_qtables(qtables):
qtables = [qtables[key] for key in range(len(qtables)) if key in qtables]
for idx, table in enumerate(qtables):
qtables[idx] = [table[i] for i in zigzag_index]
return qtables
def get_sampling(im):
sampling = im.layer[0][1:3] + im.layer[1][1:3] + im.layer[2][1:3]
return samplings.get(sampling, -1)
def _save(im, fp, filename):
try:
rawmode = RAWMODE[im.mode]
except KeyError:
raise IOError("cannot write mode %s as JPEG" % im.mode)
info = im.encoderinfo
dpi = info.get("dpi", (0, 0))
quality = info.get("quality", 0)
subsampling = info.get("subsampling", -1)
qtables = info.get("qtables")
if quality == "keep":
quality = 0
subsampling = "keep"
qtables = "keep"
elif quality in presets:
preset = presets[quality]
quality = 0
subsampling = preset.get('subsampling', -1)
qtables = preset.get('quantization')
elif not isinstance(quality, int):
raise ValueError("Invalid quality setting")
else:
if subsampling in presets:
subsampling = presets[subsampling].get('subsampling', -1)
if isStringType(qtables) and qtables in presets:
qtables = presets[qtables].get('quantization')
if subsampling == "4:4:4":
subsampling = 0
elif subsampling == "4:2:2":
subsampling = 1
elif subsampling == "4:1:1":
subsampling = 2
elif subsampling == "keep":
if im.format != "JPEG":
raise ValueError("Cannot use 'keep' when original image is not a JPEG")
subsampling = get_sampling(im)
def validate_qtables(qtables):
if qtables is None:
return qtables
if isStringType(qtables):
try:
lines = [int(num) for line in qtables.splitlines()
for num in line.split('#', 1)[0].split()]
except ValueError:
raise ValueError("Invalid quantization table")
else:
qtables = [lines[s:s+64] for s in range(0, len(lines), 64)]
if isinstance(qtables, (tuple, list, dict)):
if isinstance(qtables, dict):
qtables = convert_dict_qtables(qtables)
elif isinstance(qtables, tuple):
qtables = list(qtables)
if not (0 < len(qtables) < 5):
raise ValueError("None or too many quantization tables")
for idx, table in enumerate(qtables):
try:
if len(table) != 64:
raise
table = array.array('b', table)
except TypeError:
raise ValueError("Invalid quantization table")
else:
qtables[idx] = list(table)
return qtables
if qtables == "keep":
if im.format != "JPEG":
raise ValueError("Cannot use 'keep' when original image is not a JPEG")
qtables = getattr(im, "quantization", None)
qtables = validate_qtables(qtables)
extra = b""
icc_profile = info.get("icc_profile")
if icc_profile:
ICC_OVERHEAD_LEN = 14
MAX_BYTES_IN_MARKER = 65533
MAX_DATA_BYTES_IN_MARKER = MAX_BYTES_IN_MARKER - ICC_OVERHEAD_LEN
markers = []
while icc_profile:
markers.append(icc_profile[:MAX_DATA_BYTES_IN_MARKER])
icc_profile = icc_profile[MAX_DATA_BYTES_IN_MARKER:]
i = 1
for marker in markers:
size = struct.pack(">H", 2 + ICC_OVERHEAD_LEN + len(marker))
extra += b"\xFF\xE2" + size + b"ICC_PROFILE\0" + o8(i) + o8(len(markers)) + marker
i += 1
# get keyword arguments
im.encoderconfig = (
quality,
# "progressive" is the official name, but older documentation
# says "progression"
# FIXME: issue a warning if the wrong form is used (post-1.1.7)
"progressive" in info or "progression" in info,
info.get("smooth", 0),
"optimize" in info,
info.get("streamtype", 0),
dpi[0], dpi[1],
subsampling,
qtables,
extra,
info.get("exif", b"")
)
# if we optimize, libjpeg needs a buffer big enough to hold the whole image
# in a shot. Guessing on the size, at im.size bytes. (raw pizel size is
# channels*size, this is a value that's been used in a django patch.
# https://github.com/jdriscoll/django-imagekit/issues/50
bufsize = 0
if "optimize" in info or "progressive" in info or "progression" in info:
if quality >= 95:
bufsize = 2 * im.size[0] * im.size[1]
else:
bufsize = im.size[0] * im.size[1]
# The exif info needs to be written as one block, + APP1, + one spare byte.
# Ensure that our buffer is big enough
bufsize = max(ImageFile.MAXBLOCK, bufsize, len(info.get("exif", b"")) + 5)
ImageFile._save(im, fp, [("jpeg", (0, 0)+im.size, 0, rawmode)], bufsize)
def _save_cjpeg(im, fp, filename):
# ALTERNATIVE: handle JPEGs via the IJG command line utilities.
import os
import subprocess
tempfile = im._dump()
subprocess.check_call(["cjpeg", "-outfile", filename, tempfile])
try:
os.unlink(file)
except:
pass
# -------------------------------------------------------------------q-
# Registry stuff
Image.register_open("JPEG", JpegImageFile, _accept)
Image.register_save("JPEG", _save)
Image.register_extension("JPEG", ".jfif")
Image.register_extension("JPEG", ".jpe")
Image.register_extension("JPEG", ".jpg")
Image.register_extension("JPEG", ".jpeg")
Image.register_mime("JPEG", "image/jpeg")
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