Gangmax Blog

Remove EXIF Info From JPEG File

Here is a Python script I created to remove the EXIF info from a given JPEG file.

exif_remover.py
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#! env python3
# References:
#   https://stackoverflow.com/a/27638728/3115617
#   https://www.media.mit.edu/pia/Research/deepview/exif.html
#   http://en.wikipedia.org/wiki/JPEG_File_Interchange_Format
# Licensed under GPLv3.

import sys
import struct
from typing import Union, Tuple

SOI_MARKER = b'\xff\xd8'
EOI_MARKER = b'\xff\xd9'
STRIPPED_APP_MARKERS = [
    b'\xff\xe0',    # JFIF
    b'\xff\xe1',    # EXIF
    b'\xff\xed'     # TIFF/IPTC
]

def _unpack(format: str, data: bytes, data_length: int=None) -> \
    Union[int,bytes]:
    if format == '{}s' and data_length is not None:
        format = '{}s'.format(data_length)
    return struct.unpack(format, data)[0]

def _to_int(content: bytes) -> int:
    return _unpack('>H', content)

def _is_app_marker(content: bytes) -> bool:
    value = _to_int(content)
    return value >= 0xff00 and content not in [SOI_MARKER, EOI_MARKER]

def _read(content: bytes, index: int, size: int) -> Tuple[bytes, int]:
    return content[index:index + size], index + size

def read_file(filename: str) -> bytes:
    with open(filename, 'rb') as f:
        return f.read()

def write_file(filename: str, content: bytes) -> None:
    with open(filename, 'wb') as f:
        f.write(content)

def drop_exif(source: bytes) -> bytes:
    target = bytearray()
    if len(source) <= 2 or source[0:2] != SOI_MARKER:
        # This is not a valid JPEG file.
        return source
    target += SOI_MARKER
    index = 2
    app_index = 0
    while index < len(source):
        app_marker, index = _read(source, index, 2)
        app_index += 1
        print('APP Marker[{}, {}]: {}'.format(app_index, index - 2, app_marker))
        if _is_app_marker(app_marker):
            size_bytes, index = _read(source, index, 2)
            size = _to_int(size_bytes)
            if app_marker not in STRIPPED_APP_MARKERS:
                target += app_marker
                target += source[index - 2:index - 2 + size]
                print('    NON-EXIF segment is found, copy it...')
            else:
                print('    EXIF segment is found, skip it...')
            index = index - 2 + size
        else:
            # Image stream is found, copy until the end.
            target += app_marker
            target += source[index:]
            index = len(source)
            print('    Image stream is found, copy until the end.')
    return bytes(target)

if __name__ == '__main__':
    if len(sys.argv) < 3:
        print("Usage: strip_exif.py <source.jpg> <target.jpg>")
        exit(0)
    source_file = sys.argv[1]
    target_file = sys.argv[2]
    source = read_file(source_file)
    target = drop_exif(source)
    write_file(target_file, target)
    print('Done.')

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