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.
#
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.


[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" 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), ) ]
[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) 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")