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.
#


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.
# =============================================================================
[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} 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)
[docs]class BmpRleDecoder(ImageFile.PyDecoder): _pulls_fd = True
[docs] 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) # =============================================================================
[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 _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")