#
# The Python Imaging Library
# $Id$
#
# JPEG2000 file handling
#
# History:
# 2014-03-12 ajh Created
#
# Copyright (c) 2014 Coriolis Systems Limited
# Copyright (c) 2014 Alastair Houghton
#
# See the README file for information on usage and redistribution.
#
from PIL import Image, ImageFile
import struct
import os
import io
__version__ = "0.1"
def _parse_codestream(fp):
"""Parse the JPEG 2000 codestream to extract the size and component
count from the SIZ marker segment, returning a PIL (size, mode) tuple."""
hdr = fp.read(2)
lsiz = struct.unpack('>H', hdr)[0]
siz = hdr + fp.read(lsiz - 2)
lsiz, rsiz, xsiz, ysiz, xosiz, yosiz, xtsiz, ytsiz, \
xtosiz, ytosiz, csiz \
= struct.unpack('>HHIIIIIIIIH', siz[:38])
ssiz = [None]*csiz
xrsiz = [None]*csiz
yrsiz = [None]*csiz
for i in range(csiz):
ssiz[i], xrsiz[i], yrsiz[i] \
= struct.unpack('>BBB', siz[36 + 3 * i:39 + 3 * i])
size = (xsiz - xosiz, ysiz - yosiz)
if csiz == 1:
if (yrsiz[0] & 0x7f) > 8:
mode = 'I;16'
else:
mode = 'L'
elif csiz == 2:
mode = 'LA'
elif csiz == 3:
mode = 'RGB'
elif csiz == 4:
mode = 'RGBA'
else:
mode = None
return (size, mode)
def _parse_jp2_header(fp):
"""Parse the JP2 header box to extract size, component count and
color space information, returning a PIL (size, mode) tuple."""
# Find the JP2 header box
header = None
while True:
lbox, tbox = struct.unpack('>I4s', fp.read(8))
if lbox == 1:
lbox = struct.unpack('>Q', fp.read(8))[0]
hlen = 16
else:
hlen = 8
if lbox < hlen:
raise SyntaxError('Invalid JP2 header length')
if tbox == b'jp2h':
header = fp.read(lbox - hlen)
break
else:
fp.seek(lbox - hlen, os.SEEK_CUR)
if header is None:
raise SyntaxError('could not find JP2 header')
size = None
mode = None
bpc = None
nc = None
hio = io.BytesIO(header)
while True:
lbox, tbox = struct.unpack('>I4s', hio.read(8))
if lbox == 1:
lbox = struct.unpack('>Q', hio.read(8))[0]
hlen = 16
else:
hlen = 8
content = hio.read(lbox - hlen)
if tbox == b'ihdr':
height, width, nc, bpc, c, unkc, ipr \
= struct.unpack('>IIHBBBB', content)
size = (width, height)
if unkc:
if nc == 1 and (bpc & 0x7f) > 8:
mode = 'I;16'
elif nc == 1:
mode = 'L'
elif nc == 2:
mode = 'LA'
elif nc == 3:
mode = 'RGB'
elif nc == 4:
mode = 'RGBA'
break
elif tbox == b'colr':
meth, prec, approx = struct.unpack('>BBB', content[:3])
if meth == 1:
cs = struct.unpack('>I', content[3:7])[0]
if cs == 16: # sRGB
if nc == 1 and (bpc & 0x7f) > 8:
mode = 'I;16'
elif nc == 1:
mode = 'L'
elif nc == 3:
mode = 'RGB'
elif nc == 4:
mode = 'RGBA'
break
elif cs == 17: # grayscale
if nc == 1 and (bpc & 0x7f) > 8:
mode = 'I;16'
elif nc == 1:
mode = 'L'
elif nc == 2:
mode = 'LA'
break
elif cs == 18: # sYCC
if nc == 3:
mode = 'RGB'
elif nc == 4:
mode = 'RGBA'
break
if size is None or mode is None:
raise SyntaxError("Malformed jp2 header")
return (size, mode)
##
# Image plugin for JPEG2000 images.
[文档]class Jpeg2KImageFile(ImageFile.ImageFile):
format = "JPEG2000"
format_description = "JPEG 2000 (ISO 15444)"
def _open(self):
sig = self.fp.read(4)
if sig == b'\xff\x4f\xff\x51':
self.codec = "j2k"
self.size, self.mode = _parse_codestream(self.fp)
else:
sig = sig + self.fp.read(8)
if sig == b'\x00\x00\x00\x0cjP \x0d\x0a\x87\x0a':
self.codec = "jp2"
self.size, self.mode = _parse_jp2_header(self.fp)
else:
raise SyntaxError('not a JPEG 2000 file')
if self.size is None or self.mode is None:
raise SyntaxError('unable to determine size/mode')
self.reduce = 0
self.layers = 0
fd = -1
length = -1
try:
fd = self.fp.fileno()
length = os.fstat(fd).st_size
except:
fd = -1
try:
pos = self.fp.tell()
self.fp.seek(0, 2)
length = self.fp.tell()
self.fp.seek(pos, 0)
except:
length = -1
self.tile = [('jpeg2k', (0, 0) + self.size, 0,
(self.codec, self.reduce, self.layers, fd, length))]
[文档] def load(self):
if self.reduce:
power = 1 << self.reduce
adjust = power >> 1
self.size = (int((self.size[0] + adjust) / power),
int((self.size[1] + adjust) / power))
if self.tile:
# Update the reduce and layers settings
t = self.tile[0]
t3 = (t[3][0], self.reduce, self.layers, t[3][3], t[3][4])
self.tile = [(t[0], (0, 0) + self.size, t[2], t3)]
ImageFile.ImageFile.load(self)
def _accept(prefix):
return (prefix[:4] == b'\xff\x4f\xff\x51' or
prefix[:12] == b'\x00\x00\x00\x0cjP \x0d\x0a\x87\x0a')
# ------------------------------------------------------------
# Save support
def _save(im, fp, filename):
if filename.endswith('.j2k'):
kind = 'j2k'
else:
kind = 'jp2'
# Get the keyword arguments
info = im.encoderinfo
offset = info.get('offset', None)
tile_offset = info.get('tile_offset', None)
tile_size = info.get('tile_size', None)
quality_mode = info.get('quality_mode', 'rates')
quality_layers = info.get('quality_layers', None)
num_resolutions = info.get('num_resolutions', 0)
cblk_size = info.get('codeblock_size', None)
precinct_size = info.get('precinct_size', None)
irreversible = info.get('irreversible', False)
progression = info.get('progression', 'LRCP')
cinema_mode = info.get('cinema_mode', 'no')
fd = -1
if hasattr(fp, "fileno"):
try:
fd = fp.fileno()
except:
fd = -1
im.encoderconfig = (
offset,
tile_offset,
tile_size,
quality_mode,
quality_layers,
num_resolutions,
cblk_size,
precinct_size,
irreversible,
progression,
cinema_mode,
fd
)
ImageFile._save(im, fp, [('jpeg2k', (0, 0)+im.size, 0, kind)])
# ------------------------------------------------------------
# Registry stuff
Image.register_open(Jpeg2KImageFile.format, Jpeg2KImageFile, _accept)
Image.register_save(Jpeg2KImageFile.format, _save)
Image.register_extension(Jpeg2KImageFile.format, '.jp2')
Image.register_extension(Jpeg2KImageFile.format, '.j2k')
Image.register_extension(Jpeg2KImageFile.format, '.jpc')
Image.register_extension(Jpeg2KImageFile.format, '.jpf')
Image.register_extension(Jpeg2KImageFile.format, '.jpx')
Image.register_extension(Jpeg2KImageFile.format, '.j2c')
Image.register_mime(Jpeg2KImageFile.format, 'image/jp2')
Image.register_mime(Jpeg2KImageFile.format, 'image/jpx')