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