Source code for PIL.BmpImagePlugin

#
# 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.
#


from . import Image, ImageFile, ImagePalette
from ._binary import i8, i16le as i16, i32le as i32, \
                     o8, o16le as o16, o32le as o32
import math

__version__ = "0.7"

#
# --------------------------------------------------------------------
# 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"


# ==============================================================================
# Image plugin for the Windows BMP format.
# ==============================================================================
[docs]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 } RAW, RLE8, RLE4, BITFIELDS, JPEG, PNG = 0, 1, 2, 3, 4, 5 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) file_info = {} # read bmp header size @offset 14 (this is part of the header size) file_info['header_size'] = i32(read(4)) file_info['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[0:2]) file_info['height'] = i16(header_data[2:4]) file_info['planes'] = i16(header_data[4:6]) file_info['bits'] = i16(header_data[6:8]) file_info['compression'] = self.RAW file_info['palette_padding'] = 3 # ---------------------------------------------- Windows Bitmap v2 to v5 elif file_info['header_size'] in (40, 64, 108, 124): # v3, OS/2 v2, v4, v5 if file_info['header_size'] >= 40: # v3 and OS/2 file_info['y_flip'] = i8(header_data[7]) == 0xff file_info['direction'] = 1 if file_info['y_flip'] else -1 file_info['width'] = i32(header_data[0:4]) file_info['height'] = (i32(header_data[4:8]) if not file_info['y_flip'] else 2**32 - i32(header_data[4:8])) file_info['planes'] = i16(header_data[8:10]) file_info['bits'] = i16(header_data[10:12]) file_info['compression'] = i32(header_data[12:16]) # byte size of pixel data file_info['data_size'] = i32(header_data[16:20]) file_info['pixels_per_meter'] = (i32(header_data[20:24]), i32(header_data[24:28])) file_info['colors'] = i32(header_data[28:32]) file_info['palette_padding'] = 4 self.info["dpi"] = tuple( map(lambda x: int(math.ceil(x / 39.3701)), 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*4:40+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: raise IOError("Unsupported BMP header type (%d)" % file_info['header_size']) # ------------------ 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']) # -------------------------------- Check abnormal values for DOS attacks if file_info['width'] * file_info['height'] > 2**31: raise IOError("Unsupported BMP Size: (%dx%d)" % self.size) # ----------------------- Check bit depth for unusual unsupported values self.mode, raw_mode = BIT2MODE.get(file_info['bits'], (None, None)) if self.mode is None: raise IOError("Unsupported BMP pixel depth (%d)" % file_info['bits']) # ----------------- Process BMP with Bitfields compression (not palette) if file_info['compression'] == self.BITFIELDS: SUPPORTED = { 32: [(0xff0000, 0xff00, 0xff, 0x0), (0xff0000, 0xff00, 0xff, 0xff000000), (0x0, 0x0, 0x0, 0x0), (0xff000000, 0xff0000, 0xff00, 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, (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 raw_mode in ("BGRA",) 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: raise IOError("Unsupported BMP bitfields layout") else: raise IOError("Unsupported BMP bitfields layout") elif file_info['compression'] == self.RAW: if file_info['bits'] == 32 and header == 22: # 32-bit .cur offset raw_mode, self.mode = "BGRA", "RGBA" else: raise IOError("Unsupported BMP compression (%d)" % file_info['compression']) # ---------------- 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): raise IOError("Unsupported BMP Palette size (%d)" % file_info['colors']) 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'] self.tile = [ ('raw', (0, 0, file_info['width'], file_info['height']), offset or self.fp.tell(), (raw_mode, ((file_info['width'] * file_info['bits'] + 31) >> 3) & (~3), file_info['direction'])) ] 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 head_data[0:2] != b"BM": raise SyntaxError("Not a BMP file") # read the start position of the BMP image data (u32) offset = i32(head_data[10:14]) # load bitmap information (offset=raster info) self._bitmap(offset=offset)
# ============================================================================== # Image plugin for the DIB format (BMP alias) # ==============================================================================
[docs]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 _save(im, fp, filename): try: rawmode, bits, colors = SAVE[im.mode] except KeyError: raise IOError("cannot write mode %s as BMP" % im.mode) info = im.encoderinfo dpi = info.get("dpi", (96, 96)) # 1 meter == 39.3701 inches ppm = tuple(map(lambda x: int(x * 39.3701), dpi)) stride = ((im.size[0]*bits+7)//8+3) & (~3) header = 40 # or 64 for OS/2 version 2 offset = 14 + header + colors * 4 image = stride * im.size[1] # bitmap header fp.write(b"BM" + # file type (magic) o32(offset+image) + # 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]) + o32(ppm[1]) + # resolution o32(colors) + # colors used o32(colors)) # colors important fp.write(b"\0" * (header - 40)) # padding (for OS/2 format) if im.mode == "1": for i in (0, 255): fp.write(o8(i) * 4) elif im.mode == "L": for i in range(256): fp.write(o8(i) * 4) elif im.mode == "P": fp.write(im.im.getpalette("RGB", "BGRX")) 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")