go-exif-knife: One Exif Command-Line Tool to [Nearly] Rule Them All

go-exif-knife is a tool that will allow you to parse Exif from JPEG and PNG images and to do a brute-force parse of Exif embedded in any other format. You can cherry-pick specific IFDs or tags to print, and print them both as normal and JSON-formatted text. You can can also print parsed GPS data and timestamps and even produce a Google S2 geohash from the GPS data, and dump the thumbnail. If using JPEG or PNG, you can also update or add new Exif data.

This project is built on top of go-jpeg-image-structure, go-png-image-structure, and go-exif. PNG added support for Exif only in the last year, and this project was in service of providing useful Exif support for PNG.

Binary downloads are available here.

 

 

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Go: Exif Reader/Writer Library

The go-exif project is now available. It allows you to parse and enumerate/visit/search/dump the existing IFDs/tags in an Exif blob, instantiate a builder to create and construct a new Exif blob, and create a builder from existing IFDs/tags (so you can add/remove starting from what you have). There are also utility functions to make the GPS data manageable.

There are currently 140 unit-tests in the CI process and tested examples covering enumeration, building, thumbnails, GPS, etc…

I have also published go-jpeg-image-structure and go-png-image-structure to actually implement reading/writing Exif in those corresponding formats. PNG adopted Exif support in 2017 and this project was primarily meant to provide PNG with fully-featured Exif-writer support both via library and via command-line tool.

go-exif includes a command-line utility to generally find and parse Exif data in any blob of data. This works for TIFF right off the bat (TIFF is the underlying format of Exif), which I did not specifically write a wrapper implementation for.

 

Renaming Images to Their EXIF Timestamps

EXIF is a metdata specification largely used by modern versions of JPEG and TIFF. It allows you embed a wealth of descriptive information into a picture taken by your camera. Notably, this also, usually, includes one or more timestamps. In the event that you find yourself with a directory of anonymously-named images that you’d like to rename with their timestamps, I’ve written a quick Python script to automate such a task. This script assumes that you have the exif tool installed. It’s readily available for both Linux and Mac OS.

Code

import os
import subprocess
import glob
import datetime

_PICTURE_PATH = '/my/pictures/are/here'

_EXIF_COMMAND = 'exif'
_FILESPEC = '*.jpg'
_NEW_FILENAME_TEMPLATE = '{timestamp_phrase}.jpg'
_COMMON_EXIF_TIMESTAMP_FIELD_NAME = 'Date and Time'
_EXIF_TIMESTAMP_FORMAT = '%Y:%m:%d %H:%M:%S'
_OUTPUT_TIMESTAMP_FORMAT = '%Y%m%d-%H%M%S'

def _get_exif_info(filepath):
    cmd = [_EXIF_COMMAND, '-m', filepath]
    p = subprocess.Popen(cmd, stdout=subprocess.PIPE)
    exif_tab_delimited = p.stdout.read()
    r = p.wait()
    if r != 0:
        raise ValueError("EXIF command failed: %s" % (cmd,))

    lines = exif_tab_delimited.strip().split('n')[1:]
    pairs = [l.split('t') for l in lines]
    return dict(pairs)

def _get_filepaths(path):
    full_pattern = os.path.join(path, _FILESPEC)
    for filepath in glob.glob(full_pattern):
        yield filepath

def _main():
    for original_filepath in _get_filepaths(_PICTURE_PATH):
        exif = _get_exif_info(original_filepath)

        try:
            exif_timestamp_phrase = exif[_COMMON_EXIF_TIMESTAMP_FIELD_NAME]
        except KeyError:
            print("ERROR: {0}: Missing timestamp field".format(original_filepath))
            print('')

            continue

        timestamp_dt = 
            datetime.datetime.strptime(
                exif_timestamp_phrase, 
                _EXIF_TIMESTAMP_FORMAT)

        output_timestamp_phrase = 
            timestamp_dt.strftime(_OUTPUT_TIMESTAMP_FORMAT)

        new_filename = _NEW_FILENAME_TEMPLATE.format(
                        timestamp_phrase=output_timestamp_phrase)

        new_filepath = os.path.join(path, new_filename)

        print("{0} => {1}".format(original_filepath, new_filepath))
        os.rename(original_filepath, new_filepath)

if __name__ == '__main__':
    _main()

Usage

  1. Save the script to a file.
  2. Update the value for _PICTURE_PATH to the path of your pictures.
  3. Optionally, update _FILESPEC to the correct pattern/casing of your files.
  4. Optionally, update _COMMON_EXIF_TIMESTAMP_FIELD_NAME to the correct EXIF field-name if the device that created the pictures used a different field-name (you can use the exif tool directly to explore your images).
  5. If the timestamp is not formatted using the standard colon-delimited EXIF timestamp (e.g. 2012:04:29 20:51:32), update _EXIF_TIMESTAMP_FORMAT to reflect the proper format.
  6. Run using whatever name you gave the script:
    $ python rename_images.py
    

Output

Success output will look something like:

./IMG_3871.jpg => ./20131127-143832.jpg
./IMG_3872.jpg => ./20131127-143836.jpg
./IMG_3879.jpg => ./20131127-144045.jpg
./IMG_3880.jpg => ./20131127-144105.jpg
./IMG_3927.jpg => ./20131128-172021.jpg
...