Extract BMP images from a file using Python

extract.py

# Credits: https://gist.github.com/NanoDano/e092cf9f219e4b0506743bb64d303452?permalink_comment_id=3751054#gistcomment-3751054

import os
import sys

if len(sys.argv) < 2:
    sys.exit(f"Usage: sys.argv[0] <file>")

filename = sys.argv[1]
bin = open(filename, "rb")

bin.seek(0, os.SEEK_END)  # Seek to the end

filesize = bin.tell()  # Get the file size
pos = 0
count = 0
folder = f"{filename}_extracted"

if not os.path.exists(folder):
    os.mkdir(folder)

while pos < filesize:
    bin.seek(pos)

    # Check the first 2 bytes for BMP signature
    header = bin.read(2)

    if header == b"BM":
        # Read the size (4 bytes unsigned little-endian integer) of the image
        size = int.from_bytes(bin.read(4), byteorder="little", signed=False)

        if not (size > (filesize - pos)):
            print(f"offset {hex(pos)} - {size} bytes")

            # Go back to beginning of the image
            bin.seek(pos)

            # Extract the BMP image
            image = bin.read(size)
            out = open(f"{folder}/{pos}.bmp", "wb")

            out.write(image)
            out.close()

            # Set the current position to the end of the image
            pos += size
            count += 1
        else:
            pos += 1
    else:
        # If the first 2 bytes are not a BMP header, move to the next byte
        pos += 1

bin.close()

print(f"Extracted {count} BMP image(s).")