Simple script to adjust a series of photos to add missing exif date information in a series of photos.

fill_gaps.py

#!/usr/bin/env python

# Problem: Our maternity photos were mixed digital and film,
# and the exif dates/times for the film photos were wrong, preventing
# "sort by date" working in Google Photos.
#
# Solution: the filenames are in the right order, simply interpolate
# over the gaps to inject "correct" times.


import glob
import subprocess
import datetime


def get_timestamp(path):
    result = subprocess.check_output(['exiv2', path])
    for line in result.splitlines():
        if line.startswith('Image timestamp'):
            return line.split(':', 1)[1].strip()

def get_timestamps():
    jpgs = sorted(glob.glob('*.jpg'))
    times = [(j, get_timestamp(j)) for j in jpgs]
    return times


def find_gaps(times):
    start = ''
    end = ''
    in_gap = False
    gaps = []
    for j, t in times:
        if t:
            if in_gap:
                in_gap = False
                gaps[-1][1] = t
            else:
                start = t
        else:
            if in_gap:
                gaps[-1][2].append(j)
            else:
                in_gap = True
                gaps.append([start, '', [j]])
    assert not in_gap
    return gaps


def lerp_gaps(gaps):
    TFMT = '%Y:%m:%d %H:%M:%S'
    new_times = []
    for start, end, jpgs in gaps:
        print start, end, jpgs
        s = datetime.datetime.strptime(start, TFMT)
        e = datetime.datetime.strptime(end, TFMT)
        for j in jpgs:
            s += datetime.timedelta(seconds=1)
            assert s < e, (s, e)
            t =  s.strftime(TFMT)
            new_times.append((j, t))
    return new_times


def set_times(assign):
    for j, t in assign:
        print j, t
        subprocess.check_output(['exiv2', '-Mset Exif.Image.DateTime ' + t, j])


def main():
    times = get_timestamps()

    for j, t in times:
        print j, t

    gaps = find_gaps(times)
    assign = lerp_gaps(gaps)
    set_times(assign)

    print 'done!'


if __name__ == '__main__':
    main()