how maintain exif data of images resizes using PIL

Question

when I try to resize(thumbnail) an image using PIL , it destroys the exif data associated with the image, How can I save it.

I resize the image and upload it to the cloud as image buffer.

file_path = '...'
file_name = '...'
im = Image.open( file_path )
size =(512,521)
im.thumbnail( size, Image.ANTIALIAS)
thumbnail_buf_string = StringIO.StringIO()
file_save_extension = 'JPEG'
im.save(thumbnail_buf_string, format=file_save_extension)
upload_to_cloud('512_' + file_name , thumbnail_buf_string.getvalue())

The resized image has no exif data.

Answer 1

Note: I haven't done this myself yet, but to my knowledge, PIL only allows to read exif tags but cannot write them. You will probably need gexiv2 or pyexiv2 to write the tags to your thumbnails.

UPDATE: I got curious and tried it myself :D If i got you right, you just want to copy the metadata without further modifications.

This is still crude but seems to work:

import os
import Image
import pyexiv2

fp = '/home/klaus/workspace'
fn = 'img_2380.jpg'

full_path = os.path.join(fp, fn)
print full_path

im = Image.open(full_path)
size = 512, 512
im.thumbnail(size, Image.ANTIALIAS)
im.save('bla.jpg', 'JPEG')

oldmeta = pyexiv2.ImageMetadata(full_path)
oldmeta.read()
# read metadata of the original file

newmeta = pyexiv2.ImageMetadata('bla.jpg')
newmeta.read()
# read metadata of the new file
# yes, there aren't any, but this is crucial!
# you need this class as the target for copying!

oldmeta.copy(newmeta)

newmeta.write()
# don't forget to write the data to the new file

BTW: Thanks for the interesting question!