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Pillow/PIL/JpegImagePlugin.py
Alex Clark 9a640e3157 Forking PIL
2010-07-30 22:52:47 -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, struct
import string
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 = string.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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