File size: 17,667 Bytes
b6068b4 |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 |
#
# The Python Imaging Library.
# $Id$
#
# BMP file handler
#
# Windows (and OS/2) native bitmap storage format.
#
# history:
# 1995-09-01 fl Created
# 1996-04-30 fl Added save
# 1997-08-27 fl Fixed save of 1-bit images
# 1998-03-06 fl Load P images as L where possible
# 1998-07-03 fl Load P images as 1 where possible
# 1998-12-29 fl Handle small palettes
# 2002-12-30 fl Fixed load of 1-bit palette images
# 2003-04-21 fl Fixed load of 1-bit monochrome images
# 2003-04-23 fl Added limited support for BI_BITFIELDS compression
#
# Copyright (c) 1997-2003 by Secret Labs AB
# Copyright (c) 1995-2003 by Fredrik Lundh
#
# See the README file for information on usage and redistribution.
#
import os
from . import Image, ImageFile, ImagePalette
from ._binary import i16le as i16
from ._binary import i32le as i32
from ._binary import o8
from ._binary import o16le as o16
from ._binary import o32le as o32
#
# --------------------------------------------------------------------
# Read BMP file
BIT2MODE = {
# bits => mode, rawmode
1: ("P", "P;1"),
4: ("P", "P;4"),
8: ("P", "P"),
16: ("RGB", "BGR;15"),
24: ("RGB", "BGR"),
32: ("RGB", "BGRX"),
}
def _accept(prefix):
return prefix[:2] == b"BM"
def _dib_accept(prefix):
return i32(prefix) in [12, 40, 64, 108, 124]
# =============================================================================
# Image plugin for the Windows BMP format.
# =============================================================================
class BmpImageFile(ImageFile.ImageFile):
"""Image plugin for the Windows Bitmap format (BMP)"""
# ------------------------------------------------------------- Description
format_description = "Windows Bitmap"
format = "BMP"
# -------------------------------------------------- BMP Compression values
COMPRESSIONS = {"RAW": 0, "RLE8": 1, "RLE4": 2, "BITFIELDS": 3, "JPEG": 4, "PNG": 5}
for k, v in COMPRESSIONS.items():
vars()[k] = v
def _bitmap(self, header=0, offset=0):
"""Read relevant info about the BMP"""
read, seek = self.fp.read, self.fp.seek
if header:
seek(header)
# read bmp header size @offset 14 (this is part of the header size)
file_info = {"header_size": i32(read(4)), "direction": -1}
# -------------------- If requested, read header at a specific position
# read the rest of the bmp header, without its size
header_data = ImageFile._safe_read(self.fp, file_info["header_size"] - 4)
# -------------------------------------------------- IBM OS/2 Bitmap v1
# ----- This format has different offsets because of width/height types
if file_info["header_size"] == 12:
file_info["width"] = i16(header_data, 0)
file_info["height"] = i16(header_data, 2)
file_info["planes"] = i16(header_data, 4)
file_info["bits"] = i16(header_data, 6)
file_info["compression"] = self.RAW
file_info["palette_padding"] = 3
# --------------------------------------------- Windows Bitmap v2 to v5
# v3, OS/2 v2, v4, v5
elif file_info["header_size"] in (40, 64, 108, 124):
file_info["y_flip"] = header_data[7] == 0xFF
file_info["direction"] = 1 if file_info["y_flip"] else -1
file_info["width"] = i32(header_data, 0)
file_info["height"] = (
i32(header_data, 4)
if not file_info["y_flip"]
else 2**32 - i32(header_data, 4)
)
file_info["planes"] = i16(header_data, 8)
file_info["bits"] = i16(header_data, 10)
file_info["compression"] = i32(header_data, 12)
# byte size of pixel data
file_info["data_size"] = i32(header_data, 16)
file_info["pixels_per_meter"] = (
i32(header_data, 20),
i32(header_data, 24),
)
file_info["colors"] = i32(header_data, 28)
file_info["palette_padding"] = 4
self.info["dpi"] = tuple(x / 39.3701 for x in file_info["pixels_per_meter"])
if file_info["compression"] == self.BITFIELDS:
if len(header_data) >= 52:
for idx, mask in enumerate(
["r_mask", "g_mask", "b_mask", "a_mask"]
):
file_info[mask] = i32(header_data, 36 + idx * 4)
else:
# 40 byte headers only have the three components in the
# bitfields masks, ref:
# https://msdn.microsoft.com/en-us/library/windows/desktop/dd183376(v=vs.85).aspx
# See also
# https://github.com/python-pillow/Pillow/issues/1293
# There is a 4th component in the RGBQuad, in the alpha
# location, but it is listed as a reserved component,
# and it is not generally an alpha channel
file_info["a_mask"] = 0x0
for mask in ["r_mask", "g_mask", "b_mask"]:
file_info[mask] = i32(read(4))
file_info["rgb_mask"] = (
file_info["r_mask"],
file_info["g_mask"],
file_info["b_mask"],
)
file_info["rgba_mask"] = (
file_info["r_mask"],
file_info["g_mask"],
file_info["b_mask"],
file_info["a_mask"],
)
else:
msg = f"Unsupported BMP header type ({file_info['header_size']})"
raise OSError(msg)
# ------------------ Special case : header is reported 40, which
# ---------------------- is shorter than real size for bpp >= 16
self._size = file_info["width"], file_info["height"]
# ------- If color count was not found in the header, compute from bits
file_info["colors"] = (
file_info["colors"]
if file_info.get("colors", 0)
else (1 << file_info["bits"])
)
if offset == 14 + file_info["header_size"] and file_info["bits"] <= 8:
offset += 4 * file_info["colors"]
# ---------------------- Check bit depth for unusual unsupported values
self.mode, raw_mode = BIT2MODE.get(file_info["bits"], (None, None))
if self.mode is None:
msg = f"Unsupported BMP pixel depth ({file_info['bits']})"
raise OSError(msg)
# ---------------- Process BMP with Bitfields compression (not palette)
decoder_name = "raw"
if file_info["compression"] == self.BITFIELDS:
SUPPORTED = {
32: [
(0xFF0000, 0xFF00, 0xFF, 0x0),
(0xFF000000, 0xFF0000, 0xFF00, 0x0),
(0xFF000000, 0xFF0000, 0xFF00, 0xFF),
(0xFF, 0xFF00, 0xFF0000, 0xFF000000),
(0xFF0000, 0xFF00, 0xFF, 0xFF000000),
(0x0, 0x0, 0x0, 0x0),
],
24: [(0xFF0000, 0xFF00, 0xFF)],
16: [(0xF800, 0x7E0, 0x1F), (0x7C00, 0x3E0, 0x1F)],
}
MASK_MODES = {
(32, (0xFF0000, 0xFF00, 0xFF, 0x0)): "BGRX",
(32, (0xFF000000, 0xFF0000, 0xFF00, 0x0)): "XBGR",
(32, (0xFF000000, 0xFF0000, 0xFF00, 0xFF)): "ABGR",
(32, (0xFF, 0xFF00, 0xFF0000, 0xFF000000)): "RGBA",
(32, (0xFF0000, 0xFF00, 0xFF, 0xFF000000)): "BGRA",
(32, (0x0, 0x0, 0x0, 0x0)): "BGRA",
(24, (0xFF0000, 0xFF00, 0xFF)): "BGR",
(16, (0xF800, 0x7E0, 0x1F)): "BGR;16",
(16, (0x7C00, 0x3E0, 0x1F)): "BGR;15",
}
if file_info["bits"] in SUPPORTED:
if (
file_info["bits"] == 32
and file_info["rgba_mask"] in SUPPORTED[file_info["bits"]]
):
raw_mode = MASK_MODES[(file_info["bits"], file_info["rgba_mask"])]
self.mode = "RGBA" if "A" in raw_mode else self.mode
elif (
file_info["bits"] in (24, 16)
and file_info["rgb_mask"] in SUPPORTED[file_info["bits"]]
):
raw_mode = MASK_MODES[(file_info["bits"], file_info["rgb_mask"])]
else:
msg = "Unsupported BMP bitfields layout"
raise OSError(msg)
else:
msg = "Unsupported BMP bitfields layout"
raise OSError(msg)
elif file_info["compression"] == self.RAW:
if file_info["bits"] == 32 and header == 22: # 32-bit .cur offset
raw_mode, self.mode = "BGRA", "RGBA"
elif file_info["compression"] in (self.RLE8, self.RLE4):
decoder_name = "bmp_rle"
else:
msg = f"Unsupported BMP compression ({file_info['compression']})"
raise OSError(msg)
# --------------- Once the header is processed, process the palette/LUT
if self.mode == "P": # Paletted for 1, 4 and 8 bit images
# ---------------------------------------------------- 1-bit images
if not (0 < file_info["colors"] <= 65536):
msg = f"Unsupported BMP Palette size ({file_info['colors']})"
raise OSError(msg)
else:
padding = file_info["palette_padding"]
palette = read(padding * file_info["colors"])
greyscale = True
indices = (
(0, 255)
if file_info["colors"] == 2
else list(range(file_info["colors"]))
)
# ----------------- Check if greyscale and ignore palette if so
for ind, val in enumerate(indices):
rgb = palette[ind * padding : ind * padding + 3]
if rgb != o8(val) * 3:
greyscale = False
# ------- If all colors are grey, white or black, ditch palette
if greyscale:
self.mode = "1" if file_info["colors"] == 2 else "L"
raw_mode = self.mode
else:
self.mode = "P"
self.palette = ImagePalette.raw(
"BGRX" if padding == 4 else "BGR", palette
)
# ---------------------------- Finally set the tile data for the plugin
self.info["compression"] = file_info["compression"]
args = [raw_mode]
if decoder_name == "bmp_rle":
args.append(file_info["compression"] == self.RLE4)
else:
args.append(((file_info["width"] * file_info["bits"] + 31) >> 3) & (~3))
args.append(file_info["direction"])
self.tile = [
(
decoder_name,
(0, 0, file_info["width"], file_info["height"]),
offset or self.fp.tell(),
tuple(args),
)
]
def _open(self):
"""Open file, check magic number and read header"""
# read 14 bytes: magic number, filesize, reserved, header final offset
head_data = self.fp.read(14)
# choke if the file does not have the required magic bytes
if not _accept(head_data):
msg = "Not a BMP file"
raise SyntaxError(msg)
# read the start position of the BMP image data (u32)
offset = i32(head_data, 10)
# load bitmap information (offset=raster info)
self._bitmap(offset=offset)
class BmpRleDecoder(ImageFile.PyDecoder):
_pulls_fd = True
def decode(self, buffer):
rle4 = self.args[1]
data = bytearray()
x = 0
while len(data) < self.state.xsize * self.state.ysize:
pixels = self.fd.read(1)
byte = self.fd.read(1)
if not pixels or not byte:
break
num_pixels = pixels[0]
if num_pixels:
# encoded mode
if x + num_pixels > self.state.xsize:
# Too much data for row
num_pixels = max(0, self.state.xsize - x)
if rle4:
first_pixel = o8(byte[0] >> 4)
second_pixel = o8(byte[0] & 0x0F)
for index in range(num_pixels):
if index % 2 == 0:
data += first_pixel
else:
data += second_pixel
else:
data += byte * num_pixels
x += num_pixels
else:
if byte[0] == 0:
# end of line
while len(data) % self.state.xsize != 0:
data += b"\x00"
x = 0
elif byte[0] == 1:
# end of bitmap
break
elif byte[0] == 2:
# delta
bytes_read = self.fd.read(2)
if len(bytes_read) < 2:
break
right, up = self.fd.read(2)
data += b"\x00" * (right + up * self.state.xsize)
x = len(data) % self.state.xsize
else:
# absolute mode
if rle4:
# 2 pixels per byte
byte_count = byte[0] // 2
bytes_read = self.fd.read(byte_count)
for byte_read in bytes_read:
data += o8(byte_read >> 4)
data += o8(byte_read & 0x0F)
else:
byte_count = byte[0]
bytes_read = self.fd.read(byte_count)
data += bytes_read
if len(bytes_read) < byte_count:
break
x += byte[0]
# align to 16-bit word boundary
if self.fd.tell() % 2 != 0:
self.fd.seek(1, os.SEEK_CUR)
rawmode = "L" if self.mode == "L" else "P"
self.set_as_raw(bytes(data), (rawmode, 0, self.args[-1]))
return -1, 0
# =============================================================================
# Image plugin for the DIB format (BMP alias)
# =============================================================================
class DibImageFile(BmpImageFile):
format = "DIB"
format_description = "Windows Bitmap"
def _open(self):
self._bitmap()
#
# --------------------------------------------------------------------
# Write BMP file
SAVE = {
"1": ("1", 1, 2),
"L": ("L", 8, 256),
"P": ("P", 8, 256),
"RGB": ("BGR", 24, 0),
"RGBA": ("BGRA", 32, 0),
}
def _dib_save(im, fp, filename):
_save(im, fp, filename, False)
def _save(im, fp, filename, bitmap_header=True):
try:
rawmode, bits, colors = SAVE[im.mode]
except KeyError as e:
msg = f"cannot write mode {im.mode} as BMP"
raise OSError(msg) from e
info = im.encoderinfo
dpi = info.get("dpi", (96, 96))
# 1 meter == 39.3701 inches
ppm = tuple(map(lambda x: int(x * 39.3701 + 0.5), dpi))
stride = ((im.size[0] * bits + 7) // 8 + 3) & (~3)
header = 40 # or 64 for OS/2 version 2
image = stride * im.size[1]
if im.mode == "1":
palette = b"".join(o8(i) * 4 for i in (0, 255))
elif im.mode == "L":
palette = b"".join(o8(i) * 4 for i in range(256))
elif im.mode == "P":
palette = im.im.getpalette("RGB", "BGRX")
colors = len(palette) // 4
else:
palette = None
# bitmap header
if bitmap_header:
offset = 14 + header + colors * 4
file_size = offset + image
if file_size > 2**32 - 1:
msg = "File size is too large for the BMP format"
raise ValueError(msg)
fp.write(
b"BM" # file type (magic)
+ o32(file_size) # file size
+ o32(0) # reserved
+ o32(offset) # image data offset
)
# bitmap info header
fp.write(
o32(header) # info header size
+ o32(im.size[0]) # width
+ o32(im.size[1]) # height
+ o16(1) # planes
+ o16(bits) # depth
+ o32(0) # compression (0=uncompressed)
+ o32(image) # size of bitmap
+ o32(ppm[0]) # resolution
+ o32(ppm[1]) # resolution
+ o32(colors) # colors used
+ o32(colors) # colors important
)
fp.write(b"\0" * (header - 40)) # padding (for OS/2 format)
if palette:
fp.write(palette)
ImageFile._save(im, fp, [("raw", (0, 0) + im.size, 0, (rawmode, stride, -1))])
#
# --------------------------------------------------------------------
# Registry
Image.register_open(BmpImageFile.format, BmpImageFile, _accept)
Image.register_save(BmpImageFile.format, _save)
Image.register_extension(BmpImageFile.format, ".bmp")
Image.register_mime(BmpImageFile.format, "image/bmp")
Image.register_decoder("bmp_rle", BmpRleDecoder)
Image.register_open(DibImageFile.format, DibImageFile, _dib_accept)
Image.register_save(DibImageFile.format, _dib_save)
Image.register_extension(DibImageFile.format, ".dib")
Image.register_mime(DibImageFile.format, "image/bmp")
|