Started, to re-write using pyexiv2.

Can already read DateTimeOriginal :-)

Readme.md

@@ -12,6 +12,9 @@ It then creates a `UserComment` Exif tag with the actual measured radiation at t
 Right now it depends on the following non-core Python 3 libraries:
 
   * [piexif](https://pypi.org/project/pyexif/): Python module for working with EXIF image data.
+  * [py3exiv2](https://pypi.org/project/py3exiv2/) A Python 3 binding to the library exiv2.
+  * [boost.python3](http://www.boost.org/libs/python/doc/index.html) Welcome to Boost.Python, a C++ library which enables seamless interoperability between C++ and the Python programming language.
+  * [exiv2](http://www.exiv2.org/) Exiv2 is a Cross-platform C++ library and a command line utility to manage image metadata.
 
 ## Requirements
   * GeigerCounter log file in csv format as it is being exported by the software GeigerLog. 

exif_rad.py

@@ -3,15 +3,13 @@
 
 """Iterates over a bunch of .jpg or .cr2 files and matches 
 DateTimeOriginal from Exif tag to DateTime in a csv log 
-of a GeigerMuellerCounter."""
+of a GeigerMuellerCounter. """
 
 from datetime import datetime
 import os
 import csv
 import argparse
-from PIL import Image
-import piexif
-import piexif.helper
+import pyexiv2
 
 # SIFACTOR for GQ Geiger counters
 
@@ -39,9 +37,11 @@ parser.add_argument('-o', '--outdir', type=str, default='.',
 args = parser.parse_args()
 
 for photo in args.photos:
-    # Load Image and EXIF data
-    im = Image.open(photo)
-    exif_dict = piexif.load(im.info['exif'])
+    # Load Exif data from image
+    metadata = pyexiv2.ImageMetadata(photo)
+    metadata.read()
+    tag = metadata['Exif.Photo.DateTimeOriginal']
+    picrawtime = tag.raw_value
     # Get image file name out of path
     photo_basename = os.path.basename(photo)
     
@@ -50,7 +50,6 @@ for photo in args.photos:
         csvreader = csv.reader(filter(lambda row: row[0] != '#', f), 
                                delimiter=',', skipinitialspace=True)
 
-        picrawtime = exif_dict['Exif'][piexif.ExifIFD.DateTimeOriginal].decode('ASCII')
         picisotime = datetime.strptime(picrawtime, "%Y:%m:%d %H:%M:%S")
         print('Processing file:', photo_basename, end='\r')
         for _, csvrawtime, csvrawcpm, _ in csvreader:
@@ -61,15 +60,15 @@ for photo in args.photos:
 
                 # convert str to exif compatible string
                 new_comment = 'Radiation ☢ ' + str(rad) + ' µS/h'
-                user_comment = piexif.helper.UserComment.dump(new_comment, encoding="unicode")
-                exif_dict["Exif"][piexif.ExifIFD.UserComment] = user_comment
+#                user_comment = piexif.helper.UserComment.dump(new_comment, encoding="unicode")
+#                exif_dict["Exif"][piexif.ExifIFD.UserComment] = user_comment
                 
                 # compile and write tags
-                exif_bytes = piexif.dump(exif_dict)
+#                exif_bytes = piexif.dump(exif_dict)
 
                 # be os aware and use the correct directory delimiter
                 outfile = os.path.join(args.outdir, photo_basename)
-                im.save(outfile, exif=exif_bytes)
+                # write target file
                 # print output
                 print('{:<30} {:<20} {:<22}'.format(photo_basename, str(picisotime), new_comment))
                 break