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37f22ebfcd
Pillow/PIL/JpegImagePlugin.py
Brian Crowell 37f22ebfcd py3k: Use string methods instead of string module 
First, we go for the obvious stuff. The string module methods are gone in
3.0, so we translate them to the appropriate methods on the string class.
2013-01-10 08:42:49 -06:00

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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, struct
import Image, ImageFile
def i16(c,o=0):
return ord(c[o+1]) + (ord(c[o])<<8)
def i32(c,o=0):
return ord(c[o+3]) + (ord(c[o+2])<<8) + (ord(c[o+1])<<16) + (ord(c[o])<<24)
#
# 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] == "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 = ord(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] == "Exif\0":
# extract Exif information (incomplete)
self.info["exif"] = s # FIXME: value will change
elif marker == 0xFFE2 and s[:5] == "FPXR\0":
# extract FlashPix information (incomplete)
self.info["flashpix"] = s # FIXME: value will change
elif marker == 0xFFE2 and s[:12] == "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] == "Adobe":
self.info["adobe"] = i16(s, 5)
# extract Adobe custom properties
try:
adobe_transform = ord(s[1])
except:
pass
else:
self.info["adobe_transform"] = adobe_transform
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 = ord(s[0])
if self.bits != 8:
raise SyntaxError("cannot handle %d-bit layers" % self.bits)
self.layers = ord(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 ord(self.icclist[0][13]) == len(self.icclist):
profile = []
for p in self.icclist:
profile.append(p[14:])
icc_profile = "".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], ord(t[1])/16, ord(t[1])&15, ord(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 = ord(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] == "\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 ord(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 1:
s = s + self.fp.read(1)
i = i16(s)
if MARKER.has_key(i):
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 == 65535:
# padded marker or junk; move on
s = "\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 tempfile, os
file = tempfile.mktemp()
os.system("djpeg %s >%s" % (self.filename, file))
try:
self.im = Image.core.open_ppm(file)
finally:
try: os.unlink(file)
except: pass
self.mode = self.im.mode
self.size = self.im.size
self.tile = []
def _getexif(self):
# Extract EXIF information. This method is highly experimental,
# and is likely to be replaced with something better in a future
# version.
import TiffImagePlugin, StringIO
def fixup(value):
if len(value) == 1:
return value[0]
return value
# The EXIF record consists of a TIFF file embedded in a JPEG
# application marker (!).
try:
data = self.info["exif"]
except KeyError:
return None
file = StringIO.StringIO(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
# --------------------------------------------------------------------
# stuff to save JPEG files
RAWMODE = {
"1": "L",
"L": "L",
"RGB": "RGB",
"RGBA": "RGB",
"RGBX": "RGB",
"CMYK": "CMYK;I", # assume adobe conventions
"YCbCr": "YCbCr",
}
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))
subsampling = info.get("subsampling", -1)
if subsampling == "4:4:4":
subsampling = 0
elif subsampling == "4:2:2":
subsampling = 1
elif subsampling == "4:1:1":
subsampling = 2
extra = ""
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 = extra + ("\xFF\xE2" + size + "ICC_PROFILE\0" + chr(i) + chr(len(markers)) + marker)
i = i + 1
# get keyword arguments
im.encoderconfig = (
info.get("quality", 0),
# "progressive" is the official name, but older documentation
# says "progression"
# FIXME: issue a warning if the wrong form is used (post-1.1.7)
info.has_key("progressive") or info.has_key("progression"),
info.get("smooth", 0),
info.has_key("optimize"),
info.get("streamtype", 0),
dpi[0], dpi[1],
subsampling,
extra,
)
ImageFile._save(im, fp, [("jpeg", (0,0)+im.size, 0, rawmode)])
def _save_cjpeg(im, fp, filename):
# ALTERNATIVE: handle JPEGs via the IJG command line utilities.
import os
file = im._dump()
os.system("cjpeg %s >%s" % (file, filename))
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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