Jpeg2KImagePlugin.py

#
# 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.


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),
            )
        ]

    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")