#
# 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.
#
import io
import os
import struct
from . import Image, ImageFile
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, _, _, _, _, csiz = struct.unpack_from(
">HHIIIIIIIIH", siz
)
ssiz = [None] * csiz
xrsiz = [None] * csiz
yrsiz = [None] * csiz
for i in range(csiz):
ssiz[i], xrsiz[i], yrsiz[i] = struct.unpack_from(">BBB", siz, 36 + 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 (size, mode, mimetype) tuple."""
# Find the JP2 header box
header = None
mimetype = 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
elif tbox == b"ftyp":
if fp.read(4) == b"jpx ":
mimetype = "image/jpx"
fp.seek(lbox - hlen - 4, os.SEEK_CUR)
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_from(">BBB", content)
if meth == 1:
cs = struct.unpack_from(">I", content, 3)[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, mimetype)
##
# 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"
header = _parse_jp2_header(self.fp)
self._size, self.mode, self.custom_mimetype = header
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 Exception:
fd = -1
try:
pos = self.fp.tell()
self.fp.seek(0, io.SEEK_END)
length = self.fp.tell()
self.fp.seek(pos)
except Exception:
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)]
return 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)
if quality_layers is not None and not (
isinstance(quality_layers, (list, tuple))
and all(
[
isinstance(quality_layer, (int, float))
for quality_layer in quality_layers
]
)
):
raise ValueError("quality_layers must be a sequence of numbers")
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 Exception:
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_extensions(
Jpeg2KImageFile.format, [".jp2", ".j2k", ".jpc", ".jpf", ".jpx", ".j2c"]
)
Image.register_mime(Jpeg2KImageFile.format, "image/jp2")