Aluode/PerceptionLabPortable
0
1#
2# The Python Imaging Library.
3# $Id$
4#
5# PPM support for PIL
6#
7# History:
8# 96-03-24 fl Created
9# 98-03-06 fl Write RGBA images (as RGB, that is)
10#
11# Copyright (c) Secret Labs AB 1997-98.
12# Copyright (c) Fredrik Lundh 1996.
13#
14# See the README file for information on usage and redistribution.
15#
16from __future__ import annotations
17
18import math
19from typing import IO
20
21from . import Image, ImageFile
22from ._binary import i16be as i16
23from ._binary import o8
24from ._binary import o32le as o32
25
26#
27# --------------------------------------------------------------------
28
29b_whitespace = b"\x20\x09\x0a\x0b\x0c\x0d"
30
31MODES = {
32 # standard
33 b"P1": "1",
34 b"P2": "L",
35 b"P3": "RGB",
36 b"P4": "1",
37 b"P5": "L",
38 b"P6": "RGB",
39 # extensions
40 b"P0CMYK": "CMYK",
41 b"Pf": "F",
42 # PIL extensions (for test purposes only)
43 b"PyP": "P",
44 b"PyRGBA": "RGBA",
45 b"PyCMYK": "CMYK",
46}
47
48
49def _accept(prefix: bytes) -> bool:
50 return len(prefix) >= 2 and prefix.startswith(b"P") and prefix[1] in b"0123456fy"
51
52
53##
54# Image plugin for PBM, PGM, and PPM images.
55
56
57class PpmImageFile(ImageFile.ImageFile):
58 format = "PPM"
59 format_description = "Pbmplus image"
60
61 def _read_magic(self) -> bytes:
62 assert self.fp is not None
63
64 magic = b""
65 # read until whitespace or longest available magic number
66 for _ in range(6):
67 c = self.fp.read(1)
68 if not c or c in b_whitespace:
69 break
70 magic += c
71 return magic
72
73 def _read_token(self) -> bytes:
74 assert self.fp is not None
75
76 token = b""
77 while len(token) <= 10: # read until next whitespace or limit of 10 characters
78 c = self.fp.read(1)
79 if not c:
80 break
81 elif c in b_whitespace: # token ended
82 if not token:
83 # skip whitespace at start
84 continue
85 break
86 elif c == b"#":
87 # ignores rest of the line; stops at CR, LF or EOF
88 while self.fp.read(1) not in b"\r\n":
89 pass
90 continue
91 token += c
92 if not token:
93 # Token was not even 1 byte
94 msg = "Reached EOF while reading header"
95 raise ValueError(msg)
96 elif len(token) > 10:
97 msg_too_long = b"Token too long in file header: %s" % token
98 raise ValueError(msg_too_long)
99 return token
100
101 def _open(self) -> None:
102 assert self.fp is not None
103
104 magic_number = self._read_magic()
105 try:
106 mode = MODES[magic_number]
107 except KeyError:
108 msg = "not a PPM file"
109 raise SyntaxError(msg)
110 self._mode = mode
111
112 if magic_number in (b"P1", b"P4"):
113 self.custom_mimetype = "image/x-portable-bitmap"
114 elif magic_number in (b"P2", b"P5"):
115 self.custom_mimetype = "image/x-portable-graymap"
116 elif magic_number in (b"P3", b"P6"):
117 self.custom_mimetype = "image/x-portable-pixmap"
118
119 self._size = int(self._read_token()), int(self._read_token())
120
121 decoder_name = "raw"
122 if magic_number in (b"P1", b"P2", b"P3"):
123 decoder_name = "ppm_plain"
124
125 args: str | tuple[str | int, ...]
126 if mode == "1":
127 args = "1;I"
128 elif mode == "F":
129 scale = float(self._read_token())
130 if scale == 0.0 or not math.isfinite(scale):
131 msg = "scale must be finite and non-zero"
132 raise ValueError(msg)
133 self.info["scale"] = abs(scale)
134
135 rawmode = "F;32F" if scale < 0 else "F;32BF"
136 args = (rawmode, 0, -1)
137 else:
138 maxval = int(self._read_token())
139 if not 0 < maxval < 65536:
140 msg = "maxval must be greater than 0 and less than 65536"
141 raise ValueError(msg)
142 if maxval > 255 and mode == "L":
143 self._mode = "I"
144
145 rawmode = mode
146 if decoder_name != "ppm_plain":
147 # If maxval matches a bit depth, use the raw decoder directly
148 if maxval == 65535 and mode == "L":
149 rawmode = "I;16B"
150 elif maxval != 255:
151 decoder_name = "ppm"
152
153 args = rawmode if decoder_name == "raw" else (rawmode, maxval)
154 self.tile = [
155 ImageFile._Tile(decoder_name, (0, 0) + self.size, self.fp.tell(), args)
156 ]
157
158
159#
160# --------------------------------------------------------------------
161
162
163class PpmPlainDecoder(ImageFile.PyDecoder):
164 _pulls_fd = True
165 _comment_spans: bool
166
167 def _read_block(self) -> bytes:
168 assert self.fd is not None
169
170 return self.fd.read(ImageFile.SAFEBLOCK)
171
172 def _find_comment_end(self, block: bytes, start: int = 0) -> int:
173 a = block.find(b"\n", start)
174 b = block.find(b"\r", start)
175 return min(a, b) if a * b > 0 else max(a, b) # lowest nonnegative index (or -1)
176
177 def _ignore_comments(self, block: bytes) -> bytes:
178 if self._comment_spans:
179 # Finish current comment
180 while block:
181 comment_end = self._find_comment_end(block)
182 if comment_end != -1:
183 # Comment ends in this block
184 # Delete tail of comment
185 block = block[comment_end + 1 :]
186 break
187 else:
188 # Comment spans whole block
189 # So read the next block, looking for the end
190 block = self._read_block()
191
192 # Search for any further comments
193 self._comment_spans = False
194 while True:
195 comment_start = block.find(b"#")
196 if comment_start == -1:
197 # No comment found
198 break
199 comment_end = self._find_comment_end(block, comment_start)
200 if comment_end != -1:
201 # Comment ends in this block
202 # Delete comment
203 block = block[:comment_start] + block[comment_end + 1 :]
204 else:
205 # Comment continues to next block(s)
206 block = block[:comment_start]
207 self._comment_spans = True
208 break
209 return block
210
211 def _decode_bitonal(self) -> bytearray:
212 """
213 This is a separate method because in the plain PBM format, all data tokens are
214 exactly one byte, so the inter-token whitespace is optional.
215 """
216 data = bytearray()
217 total_bytes = self.state.xsize * self.state.ysize
218
219 while len(data) != total_bytes:
220 block = self._read_block() # read next block
221 if not block:
222 # eof
223 break
224
225 block = self._ignore_comments(block)
226
227 tokens = b"".join(block.split())
228 for token in tokens:
229 if token not in (48, 49):
230 msg = b"Invalid token for this mode: %s" % bytes([token])
231 raise ValueError(msg)
232 data = (data + tokens)[:total_bytes]
233 invert = bytes.maketrans(b"01", b"\xff\x00")
234 return data.translate(invert)
235
236 def _decode_blocks(self, maxval: int) -> bytearray:
237 data = bytearray()
238 max_len = 10
239 out_byte_count = 4 if self.mode == "I" else 1
240 out_max = 65535 if self.mode == "I" else 255
241 bands = Image.getmodebands(self.mode)
242 total_bytes = self.state.xsize * self.state.ysize * bands * out_byte_count
243
244 half_token = b""
245 while len(data) != total_bytes:
246 block = self._read_block() # read next block
247 if not block:
248 if half_token:
249 block = bytearray(b" ") # flush half_token
250 else:
251 # eof
252 break
253
254 block = self._ignore_comments(block)
255
256 if half_token:
257 block = half_token + block # stitch half_token to new block
258 half_token = b""
259
260 tokens = block.split()
261
262 if block and not block[-1:].isspace(): # block might split token
263 half_token = tokens.pop() # save half token for later
264 if len(half_token) > max_len: # prevent buildup of half_token
265 msg = (
266 b"Token too long found in data: %s" % half_token[: max_len + 1]
267 )
268 raise ValueError(msg)
269
270 for token in tokens:
271 if len(token) > max_len:
272 msg = b"Token too long found in data: %s" % token[: max_len + 1]
273 raise ValueError(msg)
274 value = int(token)
275 if value < 0:
276 msg_str = f"Channel value is negative: {value}"
277 raise ValueError(msg_str)
278 if value > maxval:
279 msg_str = f"Channel value too large for this mode: {value}"
280 raise ValueError(msg_str)
281 value = round(value / maxval * out_max)
282 data += o32(value) if self.mode == "I" else o8(value)
283 if len(data) == total_bytes: # finished!
284 break
285 return data
286
287 def decode(self, buffer: bytes | Image.SupportsArrayInterface) -> tuple[int, int]:
288 self._comment_spans = False
289 if self.mode == "1":
290 data = self._decode_bitonal()
291 rawmode = "1;8"
292 else:
293 maxval = self.args[-1]
294 data = self._decode_blocks(maxval)
295 rawmode = "I;32" if self.mode == "I" else self.mode
296 self.set_as_raw(bytes(data), rawmode)
297 return -1, 0
298
299
300class PpmDecoder(ImageFile.PyDecoder):
301 _pulls_fd = True
302
303 def decode(self, buffer: bytes | Image.SupportsArrayInterface) -> tuple[int, int]:
304 assert self.fd is not None
305
306 data = bytearray()
307 maxval = self.args[-1]
308 in_byte_count = 1 if maxval < 256 else 2
309 out_byte_count = 4 if self.mode == "I" else 1
310 out_max = 65535 if self.mode == "I" else 255
311 bands = Image.getmodebands(self.mode)
312 dest_length = self.state.xsize * self.state.ysize * bands * out_byte_count
313 while len(data) < dest_length:
314 pixels = self.fd.read(in_byte_count * bands)
315 if len(pixels) < in_byte_count * bands:
316 # eof
317 break
318 for b in range(bands):
319 value = (
320 pixels[b] if in_byte_count == 1 else i16(pixels, b * in_byte_count)
321 )
322 value = min(out_max, round(value / maxval * out_max))
323 data += o32(value) if self.mode == "I" else o8(value)
324 rawmode = "I;32" if self.mode == "I" else self.mode
325 self.set_as_raw(bytes(data), rawmode)
326 return -1, 0
327
328
329#
330# --------------------------------------------------------------------
331
332
333def _save(im: Image.Image, fp: IO[bytes], filename: str | bytes) -> None:
334 if im.mode == "1":
335 rawmode, head = "1;I", b"P4"
336 elif im.mode == "L":
337 rawmode, head = "L", b"P5"
338 elif im.mode in ("I", "I;16"):
339 rawmode, head = "I;16B", b"P5"
340 elif im.mode in ("RGB", "RGBA"):
341 rawmode, head = "RGB", b"P6"
342 elif im.mode == "F":
343 rawmode, head = "F;32F", b"Pf"
344 else:
345 msg = f"cannot write mode {im.mode} as PPM"
346 raise OSError(msg)
347 fp.write(head + b"\n%d %d\n" % im.size)
348 if head == b"P6":
349 fp.write(b"255\n")
350 elif head == b"P5":
351 if rawmode == "L":
352 fp.write(b"255\n")
353 else:
354 fp.write(b"65535\n")
355 elif head == b"Pf":
356 fp.write(b"-1.0\n")
357 row_order = -1 if im.mode == "F" else 1
358 ImageFile._save(
359 im, fp, [ImageFile._Tile("raw", (0, 0) + im.size, 0, (rawmode, 0, row_order))]
360 )
361
362
363#
364# --------------------------------------------------------------------
365
366
367Image.register_open(PpmImageFile.format, PpmImageFile, _accept)
368Image.register_save(PpmImageFile.format, _save)
369
370Image.register_decoder("ppm", PpmDecoder)
371Image.register_decoder("ppm_plain", PpmPlainDecoder)
372
373Image.register_extensions(PpmImageFile.format, [".pbm", ".pgm", ".ppm", ".pnm", ".pfm"])
374
375Image.register_mime(PpmImageFile.format, "image/x-portable-anymap")
376