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1#
2# The Python Imaging Library
3# $Id$
4#
5# JPEG2000 file handling
6#
7# History:
8# 2014-03-12 ajh Created
9# 2021-06-30 rogermb Extract dpi information from the 'resc' header box
10#
11# Copyright (c) 2014 Coriolis Systems Limited
12# Copyright (c) 2014 Alastair Houghton
13#
14# See the README file for information on usage and redistribution.
15#
16from __future__ import annotations
18import io
19import os
20import struct
21from typing import cast
23from . import Image, ImageFile, ImagePalette, _binary
25TYPE_CHECKING = False
26if TYPE_CHECKING:
27 from collections.abc import Callable
28 from typing import IO
31class BoxReader:
32 """
33 A small helper class to read fields stored in JPEG2000 header boxes
34 and to easily step into and read sub-boxes.
35 """
37 def __init__(self, fp: IO[bytes], length: int = -1) -> None:
38 self.fp = fp
39 self.has_length = length >= 0
40 self.length = length
41 self.remaining_in_box = -1
43 def _can_read(self, num_bytes: int) -> bool:
44 if self.has_length and self.fp.tell() + num_bytes > self.length:
45 # Outside box: ensure we don't read past the known file length
46 return False
47 if self.remaining_in_box >= 0:
48 # Inside box contents: ensure read does not go past box boundaries
49 return num_bytes <= self.remaining_in_box
50 else:
51 return True # No length known, just read
53 def _read_bytes(self, num_bytes: int) -> bytes:
54 if not self._can_read(num_bytes):
55 msg = "Not enough data in header"
56 raise SyntaxError(msg)
58 data = self.fp.read(num_bytes)
59 if len(data) < num_bytes:
60 msg = f"Expected to read {num_bytes} bytes but only got {len(data)}."
61 raise OSError(msg)
63 if self.remaining_in_box > 0:
64 self.remaining_in_box -= num_bytes
65 return data
67 def read_fields(self, field_format: str) -> tuple[int | bytes, ...]:
68 size = struct.calcsize(field_format)
69 data = self._read_bytes(size)
70 return struct.unpack(field_format, data)
72 def read_boxes(self) -> BoxReader:
73 size = self.remaining_in_box
74 data = self._read_bytes(size)
75 return BoxReader(io.BytesIO(data), size)
77 def has_next_box(self) -> bool:
78 if self.has_length:
79 return self.fp.tell() + self.remaining_in_box < self.length
80 else:
81 return True
83 def next_box_type(self) -> bytes:
84 # Skip the rest of the box if it has not been read
85 if self.remaining_in_box > 0:
86 self.fp.seek(self.remaining_in_box, os.SEEK_CUR)
87 self.remaining_in_box = -1
89 # Read the length and type of the next box
90 lbox, tbox = cast(tuple[int, bytes], self.read_fields(">I4s"))
91 if lbox == 1:
92 lbox = cast(int, self.read_fields(">Q")[0])
93 hlen = 16
94 else:
95 hlen = 8
97 if lbox < hlen or not self._can_read(lbox - hlen):
98 msg = "Invalid header length"
99 raise SyntaxError(msg)
101 self.remaining_in_box = lbox - hlen
102 return tbox
105def _parse_codestream(fp: IO[bytes]) -> tuple[tuple[int, int], str]:
106 """Parse the JPEG 2000 codestream to extract the size and component
107 count from the SIZ marker segment, returning a PIL (size, mode) tuple."""
109 hdr = fp.read(2)
110 lsiz = _binary.i16be(hdr)
111 siz = hdr + fp.read(lsiz - 2)
112 lsiz, rsiz, xsiz, ysiz, xosiz, yosiz, _, _, _, _, csiz = struct.unpack_from(
113 ">HHIIIIIIIIH", siz
114 )
116 size = (xsiz - xosiz, ysiz - yosiz)
117 if csiz == 1:
118 ssiz = struct.unpack_from(">B", siz, 38)
119 if (ssiz[0] & 0x7F) + 1 > 8:
120 mode = "I;16"
121 else:
122 mode = "L"
123 elif csiz == 2:
124 mode = "LA"
125 elif csiz == 3:
126 mode = "RGB"
127 elif csiz == 4:
128 mode = "RGBA"
129 else:
130 msg = "unable to determine J2K image mode"
131 raise SyntaxError(msg)
133 return size, mode
136def _res_to_dpi(num: int, denom: int, exp: int) -> float | None:
137 """Convert JPEG2000's (numerator, denominator, exponent-base-10) resolution,
138 calculated as (num / denom) * 10^exp and stored in dots per meter,
139 to floating-point dots per inch."""
140 if denom == 0:
141 return None
142 return (254 * num * (10**exp)) / (10000 * denom)
145def _parse_jp2_header(
146 fp: IO[bytes],
147) -> tuple[
148 tuple[int, int],
149 str,
150 str | None,
151 tuple[float, float] | None,
152 ImagePalette.ImagePalette | None,
153]:
154 """Parse the JP2 header box to extract size, component count,
155 color space information, and optionally DPI information,
156 returning a (size, mode, mimetype, dpi) tuple."""
158 # Find the JP2 header box
159 reader = BoxReader(fp)
160 header = None
161 mimetype = None
162 while reader.has_next_box():
163 tbox = reader.next_box_type()
165 if tbox == b"jp2h":
166 header = reader.read_boxes()
167 break
168 elif tbox == b"ftyp":
169 if reader.read_fields(">4s")[0] == b"jpx ":
170 mimetype = "image/jpx"
171 assert header is not None
173 size = None
174 mode = None
175 bpc = None
176 nc = None
177 dpi = None # 2-tuple of DPI info, or None
178 palette = None
179 cmyk = False
181 while header.has_next_box():
182 tbox = header.next_box_type()
184 if tbox == b"ihdr":
185 height, width, nc, bpc = header.read_fields(">IIHB")
186 assert isinstance(height, int)
187 assert isinstance(width, int)
188 assert isinstance(bpc, int)
189 size = (width, height)
190 if nc == 1 and (bpc & 0x7F) > 8:
191 mode = "I;16"
192 elif nc == 1:
193 mode = "L"
194 elif nc == 2:
195 mode = "LA"
196 elif nc == 3:
197 mode = "RGB"
198 elif nc == 4:
199 mode = "RGBA"
200 elif tbox == b"colr":
201 meth, _, _, enumcs = header.read_fields(">BBBI")
202 if cmyk := (meth == 1 and enumcs == 12):
203 if nc == 4:
204 mode = "CMYK"
205 elif tbox == b"pclr" and mode in ("L", "LA"):
206 ne, npc = header.read_fields(">HB")
207 assert isinstance(ne, int)
208 assert isinstance(npc, int)
209 max_bitdepth = 0
210 for bitdepth in header.read_fields(">" + ("B" * npc)):
211 assert isinstance(bitdepth, int)
212 if bitdepth > max_bitdepth:
213 max_bitdepth = bitdepth
214 if max_bitdepth <= 8:
215 if npc == 4:
216 palette_mode = "CMYK" if cmyk else "RGBA"
217 else:
218 palette_mode = "RGB"
219 palette = ImagePalette.ImagePalette(palette_mode)
220 for i in range(ne):
221 color: list[int] = []
222 for value in header.read_fields(">" + ("B" * npc)):
223 assert isinstance(value, int)
224 color.append(value)
225 palette.getcolor(tuple(color))
226 mode = "P" if mode == "L" else "PA"
227 elif tbox == b"res ":
228 res = header.read_boxes()
229 while res.has_next_box():
230 tres = res.next_box_type()
231 if tres == b"resc":
232 vrcn, vrcd, hrcn, hrcd, vrce, hrce = res.read_fields(">HHHHBB")
233 assert isinstance(vrcn, int)
234 assert isinstance(vrcd, int)
235 assert isinstance(hrcn, int)
236 assert isinstance(hrcd, int)
237 assert isinstance(vrce, int)
238 assert isinstance(hrce, int)
239 hres = _res_to_dpi(hrcn, hrcd, hrce)
240 vres = _res_to_dpi(vrcn, vrcd, vrce)
241 if hres is not None and vres is not None:
242 dpi = (hres, vres)
243 break
245 if size is None or mode is None:
246 msg = "Malformed JP2 header"
247 raise SyntaxError(msg)
249 return size, mode, mimetype, dpi, palette
252##
253# Image plugin for JPEG2000 images.
256class Jpeg2KImageFile(ImageFile.ImageFile):
257 format = "JPEG2000"
258 format_description = "JPEG 2000 (ISO 15444)"
260 def _open(self) -> None:
261 assert self.fp is not None
262 sig = self.fp.read(4)
263 if sig == b"\xff\x4f\xff\x51":
264 self.codec = "j2k"
265 self._size, self._mode = _parse_codestream(self.fp)
266 self._parse_comment()
267 else:
268 sig = sig + self.fp.read(8)
270 if sig == b"\x00\x00\x00\x0cjP \x0d\x0a\x87\x0a":
271 self.codec = "jp2"
272 header = _parse_jp2_header(self.fp)
273 self._size, self._mode, self.custom_mimetype, dpi, self.palette = header
274 if dpi is not None:
275 self.info["dpi"] = dpi
276 if self.fp.read(12).endswith(b"jp2c\xff\x4f\xff\x51"):
277 hdr = self.fp.read(2)
278 length = _binary.i16be(hdr)
279 self.fp.seek(length - 2, os.SEEK_CUR)
280 self._parse_comment()
281 else:
282 msg = "not a JPEG 2000 file"
283 raise SyntaxError(msg)
285 self._reduce = 0
286 self.layers = 0
288 fd = -1
289 length = -1
291 try:
292 fd = self.fp.fileno()
293 length = os.fstat(fd).st_size
294 except Exception:
295 fd = -1
296 try:
297 pos = self.fp.tell()
298 self.fp.seek(0, io.SEEK_END)
299 length = self.fp.tell()
300 self.fp.seek(pos)
301 except Exception:
302 length = -1
304 self.tile = [
305 ImageFile._Tile(
306 "jpeg2k",
307 (0, 0) + self.size,
308 0,
309 (self.codec, self._reduce, self.layers, fd, length),
310 )
311 ]
313 def _parse_comment(self) -> None:
314 assert self.fp is not None
315 while True:
316 marker = self.fp.read(2)
317 if not marker:
318 break
319 typ = marker[1]
320 if typ in (0x90, 0xD9):
321 # Start of tile or end of codestream
322 break
323 hdr = self.fp.read(2)
324 length = _binary.i16be(hdr)
325 if typ == 0x64:
326 # Comment
327 self.info["comment"] = self.fp.read(length - 2)[2:]
328 break
329 else:
330 self.fp.seek(length - 2, os.SEEK_CUR)
332 @property # type: ignore[override]
333 def reduce(
334 self,
335 ) -> (
336 Callable[[int | tuple[int, int], tuple[int, int, int, int] | None], Image.Image]
337 | int
338 ):
339 # https://github.com/python-pillow/Pillow/issues/4343 found that the
340 # new Image 'reduce' method was shadowed by this plugin's 'reduce'
341 # property. This attempts to allow for both scenarios
342 return self._reduce or super().reduce
344 @reduce.setter
345 def reduce(self, value: int) -> None:
346 self._reduce = value
348 def load(self) -> Image.core.PixelAccess | None:
349 if self.tile and self._reduce:
350 power = 1 << self._reduce
351 adjust = power >> 1
352 self._size = (
353 int((self.size[0] + adjust) / power),
354 int((self.size[1] + adjust) / power),
355 )
357 # Update the reduce and layers settings
358 t = self.tile[0]
359 assert isinstance(t[3], tuple)
360 t3 = (t[3][0], self._reduce, self.layers, t[3][3], t[3][4])
361 self.tile = [ImageFile._Tile(t[0], (0, 0) + self.size, t[2], t3)]
363 return ImageFile.ImageFile.load(self)
366def _accept(prefix: bytes) -> bool:
367 return prefix.startswith(
368 (b"\xff\x4f\xff\x51", b"\x00\x00\x00\x0cjP \x0d\x0a\x87\x0a")
369 )
372# ------------------------------------------------------------
373# Save support
376def _save(im: Image.Image, fp: IO[bytes], filename: str | bytes) -> None:
377 # Get the keyword arguments
378 info = im.encoderinfo
380 if isinstance(filename, str):
381 filename = filename.encode()
382 if filename.endswith(b".j2k") or info.get("no_jp2", False):
383 kind = "j2k"
384 else:
385 kind = "jp2"
387 offset = info.get("offset", None)
388 tile_offset = info.get("tile_offset", None)
389 tile_size = info.get("tile_size", None)
390 quality_mode = info.get("quality_mode", "rates")
391 quality_layers = info.get("quality_layers", None)
392 if quality_layers is not None and not (
393 isinstance(quality_layers, (list, tuple))
394 and all(
395 isinstance(quality_layer, (int, float)) for quality_layer in quality_layers
396 )
397 ):
398 msg = "quality_layers must be a sequence of numbers"
399 raise ValueError(msg)
401 num_resolutions = info.get("num_resolutions", 0)
402 cblk_size = info.get("codeblock_size", None)
403 precinct_size = info.get("precinct_size", None)
404 irreversible = info.get("irreversible", False)
405 progression = info.get("progression", "LRCP")
406 cinema_mode = info.get("cinema_mode", "no")
407 mct = info.get("mct", 0)
408 signed = info.get("signed", False)
409 comment = info.get("comment")
410 if isinstance(comment, str):
411 comment = comment.encode()
412 plt = info.get("plt", False)
414 fd = -1
415 if hasattr(fp, "fileno"):
416 try:
417 fd = fp.fileno()
418 except Exception:
419 fd = -1
421 im.encoderconfig = (
422 offset,
423 tile_offset,
424 tile_size,
425 quality_mode,
426 quality_layers,
427 num_resolutions,
428 cblk_size,
429 precinct_size,
430 irreversible,
431 progression,
432 cinema_mode,
433 mct,
434 signed,
435 fd,
436 comment,
437 plt,
438 )
440 ImageFile._save(im, fp, [ImageFile._Tile("jpeg2k", (0, 0) + im.size, 0, kind)])
443# ------------------------------------------------------------
444# Registry stuff
447Image.register_open(Jpeg2KImageFile.format, Jpeg2KImageFile, _accept)
448Image.register_save(Jpeg2KImageFile.format, _save)
450Image.register_extensions(
451 Jpeg2KImageFile.format, [".jp2", ".j2k", ".jpc", ".jpf", ".jpx", ".j2c"]
452)
454Image.register_mime(Jpeg2KImageFile.format, "image/jp2")