The markphotos.py script adds a copyright notice to JPEG pictures as metadata.
Update: This script was moved to my scripts repo on github on 2017-12-28.
It is written in python (version 3) and uses exiftool. This is not a visible notice, but one contained in the file’s metadata. The following in an excerpt from the identify --verbose output of a photos that was marked by markphotos.py:
Image: img_0541.jpg Format: JPEG (Joint Photographic Experts Group JFIF format) Class: DirectClass Geometry: 3648x2736+0+0 Resolution: 180x180 Print size: 20.2667x15.2 Units: PixelsPerInch Type: TrueColor ... Properties: comment: Copyright © 2011 R.F. Smith <firstname.lastname@example.org> ... exif:DateTime: 2011:06:08 21:53:32
To speed up the processing of multiple pictures, this script runs in parallel on all the cores that your machine has. If you want to add a visual watermark to a picture, I suggest using the mogrify program from the ImageMagick suite.
Edit the script and change the string cr in the function processfile to something appropriate before using this script!