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- #
- # The Python Imaging Library
- # $Id$
- #
- # JPEG2000 file handling
- #
- # History:
- # 2014-03-12 ajh Created
- # 2021-06-30 rogermb Extract dpi information from the 'resc' header box
- #
- # 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, _binary
-
-
- class BoxReader:
- """
- A small helper class to read fields stored in JPEG2000 header boxes
- and to easily step into and read sub-boxes.
- """
-
- def __init__(self, fp, length=-1):
- self.fp = fp
- self.has_length = length >= 0
- self.length = length
- self.remaining_in_box = -1
-
- def _can_read(self, num_bytes):
- if self.has_length and self.fp.tell() + num_bytes > self.length:
- # Outside box: ensure we don't read past the known file length
- return False
- if self.remaining_in_box >= 0:
- # Inside box contents: ensure read does not go past box boundaries
- return num_bytes <= self.remaining_in_box
- else:
- return True # No length known, just read
-
- def _read_bytes(self, num_bytes):
- if not self._can_read(num_bytes):
- msg = "Not enough data in header"
- raise SyntaxError(msg)
-
- data = self.fp.read(num_bytes)
- if len(data) < num_bytes:
- msg = f"Expected to read {num_bytes} bytes but only got {len(data)}."
- raise OSError(msg)
-
- if self.remaining_in_box > 0:
- self.remaining_in_box -= num_bytes
- return data
-
- def read_fields(self, field_format):
- size = struct.calcsize(field_format)
- data = self._read_bytes(size)
- return struct.unpack(field_format, data)
-
- def read_boxes(self):
- size = self.remaining_in_box
- data = self._read_bytes(size)
- return BoxReader(io.BytesIO(data), size)
-
- def has_next_box(self):
- if self.has_length:
- return self.fp.tell() + self.remaining_in_box < self.length
- else:
- return True
-
- def next_box_type(self):
- # Skip the rest of the box if it has not been read
- if self.remaining_in_box > 0:
- self.fp.seek(self.remaining_in_box, os.SEEK_CUR)
- self.remaining_in_box = -1
-
- # Read the length and type of the next box
- lbox, tbox = self.read_fields(">I4s")
- if lbox == 1:
- lbox = self.read_fields(">Q")[0]
- hlen = 16
- else:
- hlen = 8
-
- if lbox < hlen or not self._can_read(lbox - hlen):
- msg = "Invalid header length"
- raise SyntaxError(msg)
-
- self.remaining_in_box = lbox - hlen
- return tbox
-
-
- 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 = _binary.i16be(hdr)
- 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 _res_to_dpi(num, denom, exp):
- """Convert JPEG2000's (numerator, denominator, exponent-base-10) resolution,
- calculated as (num / denom) * 10^exp and stored in dots per meter,
- to floating-point dots per inch."""
- if denom != 0:
- return (254 * num * (10**exp)) / (10000 * denom)
-
-
- def _parse_jp2_header(fp):
- """Parse the JP2 header box to extract size, component count,
- color space information, and optionally DPI information,
- returning a (size, mode, mimetype, dpi) tuple."""
-
- # Find the JP2 header box
- reader = BoxReader(fp)
- header = None
- mimetype = None
- while reader.has_next_box():
- tbox = reader.next_box_type()
-
- if tbox == b"jp2h":
- header = reader.read_boxes()
- break
- elif tbox == b"ftyp":
- if reader.read_fields(">4s")[0] == b"jpx ":
- mimetype = "image/jpx"
-
- size = None
- mode = None
- bpc = None
- nc = None
- dpi = None # 2-tuple of DPI info, or None
-
- while header.has_next_box():
- tbox = header.next_box_type()
-
- if tbox == b"ihdr":
- height, width, nc, bpc = header.read_fields(">IIHB")
- size = (width, height)
- 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"
- elif tbox == b"res ":
- res = header.read_boxes()
- while res.has_next_box():
- tres = res.next_box_type()
- if tres == b"resc":
- vrcn, vrcd, hrcn, hrcd, vrce, hrce = res.read_fields(">HHHHBB")
- hres = _res_to_dpi(hrcn, hrcd, hrce)
- vres = _res_to_dpi(vrcn, vrcd, vrce)
- if hres is not None and vres is not None:
- dpi = (hres, vres)
- break
-
- if size is None or mode is None:
- msg = "Malformed JP2 header"
- raise SyntaxError(msg)
-
- return size, mode, mimetype, dpi
-
-
- ##
- # 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, dpi = header
- if dpi is not None:
- self.info["dpi"] = dpi
- if self.fp.read(12).endswith(b"jp2c\xff\x4f\xff\x51"):
- self._parse_comment()
- else:
- msg = "not a JPEG 2000 file"
- raise SyntaxError(msg)
-
- if self.size is None or self.mode is None:
- msg = "unable to determine size/mode"
- raise SyntaxError(msg)
-
- 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 _parse_comment(self):
- hdr = self.fp.read(2)
- length = _binary.i16be(hdr)
- self.fp.seek(length - 2, os.SEEK_CUR)
-
- while True:
- marker = self.fp.read(2)
- if not marker:
- break
- typ = marker[1]
- if typ in (0x90, 0xD9):
- # Start of tile or end of codestream
- break
- hdr = self.fp.read(2)
- length = _binary.i16be(hdr)
- if typ == 0x64:
- # Comment
- self.info["comment"] = self.fp.read(length - 2)[2:]
- break
- else:
- self.fp.seek(length - 2, os.SEEK_CUR)
-
- @property
- def reduce(self):
- # https://github.com/python-pillow/Pillow/issues/4343 found that the
- # new Image 'reduce' method was shadowed by this plugin's 'reduce'
- # property. This attempts to allow for both scenarios
- return self._reduce or super().reduce
-
- @reduce.setter
- def reduce(self, value):
- self._reduce = value
-
- def load(self):
- if self.tile and self._reduce:
- power = 1 << self._reduce
- adjust = power >> 1
- self._size = (
- int((self.size[0] + adjust) / power),
- int((self.size[1] + adjust) / power),
- )
-
- # 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):
- # Get the keyword arguments
- info = im.encoderinfo
-
- if filename.endswith(".j2k") or info.get("no_jp2", False):
- kind = "j2k"
- else:
- kind = "jp2"
-
- 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
- ]
- )
- ):
- msg = "quality_layers must be a sequence of numbers"
- raise ValueError(msg)
-
- 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")
- mct = info.get("mct", 0)
- signed = info.get("signed", False)
- comment = info.get("comment")
- if isinstance(comment, str):
- comment = comment.encode()
- plt = info.get("plt", False)
-
- 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,
- mct,
- signed,
- fd,
- comment,
- plt,
- )
-
- 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")
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