Source code for PIL.Jpeg2KImagePlugin

#
# 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 . 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_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 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_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)

##
# Image plugin for JPEG2000 images.


[docs]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))]
[docs] 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) 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_extensions(Jpeg2KImageFile.format, [".jp2", ".j2k", ".jpc", ".jpf", ".jpx", ".j2c"]) Image.register_mime(Jpeg2KImageFile.format, 'image/jp2') Image.register_mime(Jpeg2KImageFile.format, 'image/jpx')