251 lines
6.7 KiB
Python
251 lines
6.7 KiB
Python
#
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# The Python Imaging Library.
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# $Id$
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#
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# BMP file handler
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#
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# Windows (and OS/2) native bitmap storage format.
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#
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# history:
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# 1995-09-01 fl Created
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# 1996-04-30 fl Added save
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# 1997-08-27 fl Fixed save of 1-bit images
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# 1998-03-06 fl Load P images as L where possible
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# 1998-07-03 fl Load P images as 1 where possible
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# 1998-12-29 fl Handle small palettes
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# 2002-12-30 fl Fixed load of 1-bit palette images
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# 2003-04-21 fl Fixed load of 1-bit monochrome images
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# 2003-04-23 fl Added limited support for BI_BITFIELDS compression
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#
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# Copyright (c) 1997-2003 by Secret Labs AB
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# Copyright (c) 1995-2003 by Fredrik Lundh
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#
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# See the README file for information on usage and redistribution.
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#
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__version__ = "0.7"
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import string
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import Image, ImageFile, ImagePalette
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#
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# --------------------------------------------------------------------
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# Read BMP file
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def i16(c):
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return ord(c[0]) + (ord(c[1])<<8)
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def i32(c):
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return ord(c[0]) + (ord(c[1])<<8) + (ord(c[2])<<16) + (ord(c[3])<<24)
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BIT2MODE = {
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# bits => mode, rawmode
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1: ("P", "P;1"),
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4: ("P", "P;4"),
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8: ("P", "P"),
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16: ("RGB", "BGR;15"),
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24: ("RGB", "BGR"),
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32: ("RGB", "BGRX")
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}
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def _accept(prefix):
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return prefix[:2] == "BM"
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##
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# Image plugin for the Windows BMP format.
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class BmpImageFile(ImageFile.ImageFile):
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format = "BMP"
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format_description = "Windows Bitmap"
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def _bitmap(self, header = 0, offset = 0):
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if header:
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self.fp.seek(header)
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read = self.fp.read
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# CORE/INFO
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s = read(4)
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s = s + ImageFile._safe_read(self.fp, i32(s)-4)
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if len(s) == 12:
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# OS/2 1.0 CORE
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bits = i16(s[10:])
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self.size = i16(s[4:]), i16(s[6:])
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compression = 0
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lutsize = 3
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colors = 0
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direction = -1
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elif len(s) in [40, 64]:
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# WIN 3.1 or OS/2 2.0 INFO
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bits = i16(s[14:])
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self.size = i32(s[4:]), i32(s[8:])
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compression = i32(s[16:])
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lutsize = 4
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colors = i32(s[32:])
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direction = -1
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if s[11] == '\xff':
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# upside-down storage
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self.size = self.size[0], 2**32 - self.size[1]
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direction = 0
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else:
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raise IOError("Unsupported BMP header type (%d)" % len(s))
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if not colors:
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colors = 1 << bits
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# MODE
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try:
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self.mode, rawmode = BIT2MODE[bits]
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except KeyError:
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raise IOError("Unsupported BMP pixel depth (%d)" % bits)
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if compression == 3:
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# BI_BITFIELDS compression
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mask = i32(read(4)), i32(read(4)), i32(read(4))
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if bits == 32 and mask == (0xff0000, 0x00ff00, 0x0000ff):
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rawmode = "BGRX"
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elif bits == 16 and mask == (0x00f800, 0x0007e0, 0x00001f):
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rawmode = "BGR;16"
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elif bits == 16 and mask == (0x007c00, 0x0003e0, 0x00001f):
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rawmode = "BGR;15"
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else:
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# print bits, map(hex, mask)
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raise IOError("Unsupported BMP bitfields layout")
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elif compression != 0:
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raise IOError("Unsupported BMP compression (%d)" % compression)
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# LUT
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if self.mode == "P":
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palette = []
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greyscale = 1
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if colors == 2:
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indices = (0, 255)
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else:
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indices = range(colors)
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for i in indices:
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rgb = read(lutsize)[:3]
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if rgb != chr(i)*3:
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greyscale = 0
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palette.append(rgb)
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if greyscale:
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if colors == 2:
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self.mode = rawmode = "1"
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else:
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self.mode = rawmode = "L"
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else:
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self.mode = "P"
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self.palette = ImagePalette.raw(
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"BGR", string.join(palette, "")
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)
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if not offset:
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offset = self.fp.tell()
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self.tile = [("raw",
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(0, 0) + self.size,
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offset,
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(rawmode, ((self.size[0]*bits+31)>>3)&(~3), direction))]
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self.info["compression"] = compression
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def _open(self):
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# HEAD
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s = self.fp.read(14)
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if s[:2] != "BM":
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raise SyntaxError("Not a BMP file")
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offset = i32(s[10:])
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self._bitmap(offset=offset)
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class DibImageFile(BmpImageFile):
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format = "DIB"
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format_description = "Windows Bitmap"
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def _open(self):
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self._bitmap()
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#
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# --------------------------------------------------------------------
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# Write BMP file
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def o16(i):
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return chr(i&255) + chr(i>>8&255)
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def o32(i):
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return chr(i&255) + chr(i>>8&255) + chr(i>>16&255) + chr(i>>24&255)
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SAVE = {
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"1": ("1", 1, 2),
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"L": ("L", 8, 256),
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"P": ("P", 8, 256),
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"RGB": ("BGR", 24, 0),
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}
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def _save(im, fp, filename, check=0):
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try:
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rawmode, bits, colors = SAVE[im.mode]
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except KeyError:
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raise IOError("cannot write mode %s as BMP" % im.mode)
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if check:
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return check
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stride = ((im.size[0]*bits+7)/8+3)&(~3)
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header = 40 # or 64 for OS/2 version 2
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offset = 14 + header + colors * 4
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image = stride * im.size[1]
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# bitmap header
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fp.write("BM" + # file type (magic)
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o32(offset+image) + # file size
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o32(0) + # reserved
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o32(offset)) # image data offset
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# bitmap info header
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fp.write(o32(header) + # info header size
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o32(im.size[0]) + # width
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o32(im.size[1]) + # height
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o16(1) + # planes
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o16(bits) + # depth
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o32(0) + # compression (0=uncompressed)
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o32(image) + # size of bitmap
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o32(1) + o32(1) + # resolution
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o32(colors) + # colors used
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o32(colors)) # colors important
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fp.write("\000" * (header - 40)) # padding (for OS/2 format)
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if im.mode == "1":
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for i in (0, 255):
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fp.write(chr(i) * 4)
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elif im.mode == "L":
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for i in range(256):
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fp.write(chr(i) * 4)
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elif im.mode == "P":
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fp.write(im.im.getpalette("RGB", "BGRX"))
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ImageFile._save(im, fp, [("raw", (0,0)+im.size, 0, (rawmode, stride, -1))])
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#
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# --------------------------------------------------------------------
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# Registry
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Image.register_open(BmpImageFile.format, BmpImageFile, _accept)
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Image.register_save(BmpImageFile.format, _save)
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Image.register_extension(BmpImageFile.format, ".bmp")
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