Change EXIF data on JPEG without altering picture

Question

I change the exif on a jpeg using piexif to read and write exif data, which seems to work fine. The issue is when I read and write the jpeg, even tho I don’t change the bytes, it saves the picture with different pixels and the picture that was read. I need it to be exactly the same pixels. I understand this is because jpeg is a lossy format, but the only way I’ve found around it is to save it as a png and then export it as a jpeg with Mac Preview, which is not good, because I have hundreds of pictures.

def adjust_img(path):
   img = PIL.Image.open(path)
   exif_dict = piexif.load(img.info['exif'])
   new_exif = adjust_exif(exif_dict)
   exif_bytes = piexif.dump(new_exif)
   pc = path.split('/')
   stem = '/'.join(pc[:-1])
   img.save('%s/_%s' % (stem,pc[-1]), "JPEG", exif=exif_bytes, quality=95, optimize=False)

How can I preserve the picture and just alter the exif?

Asked By: syzygy

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Source

Answer 1

https://piexif.readthedocs.io/en/latest/functions.html

exif_dict = piexif.load(path)
new_exif = adjust_exif(exif_dict)
exif_bytes = piexif.dump(new_exif)
piexif.insert(exif_bytes, path)

Answered By: hMatoba

Answer 2

Exiftool is generally the way to go. But suppose you really need to edit EXIFs in your own program?

Try pyexiv2 at https://pypi.org/project/pyexiv2/.
It is recently maintained and working well. An example:

import sys
from pyexiv2 import Image as ImgMeta

DTO_KEY = 'Exif.Photo.DateTimeOriginal'
filename = sys.argv[1]


with ImgMeta(filename) as img_meta:

    exif = img_meta.read_exif()
    try:
        dto = exif[DTO_KEY]
    except KeyError:
        raise

    # Convert dto to DateTime, add TimeDelta, format as string
    # Here we skip all that to show we can simply modify it:
    new_dto_str = dto + 'Z'

    img_meta.modify_exif({DTO_KEY: new_dto_str})

When I use this I typically do the edits on a backup copy, then move it into place if happy with it.

Answered By: Gringo Suave

Change EXIF data on JPEG without altering picture

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