new_contents: import io, base64, urllib, os
  
  def pre_process(doc):
  
  	file_path = doc.image
  	file_name = os.path.basename(file_path)
  
  	if file_path.startswith('http'):
  		url = file_path
  		file_path = os.path.join('/tmp', file_name)
  		urllib.urlretrieve(url, file_path)
  
  	with io.open(file_path, 'rb') as f:
  		doc.image = base64.b64encode(f.read())
  
  	doc.image_file_name = file_name
  
  	return doc
  
  
subject: Convert image to base64 before sending Item to sync