This is just a quick update regarding digital watermarking or fingerprinting, which I am currently using with my online web images. The process embeds a digital code in each image which resists tampering and removal, remains with the image after re-editing and is trackable online. Even if an image is captured by screen grab, the digital watermark is still readable and traceable.
The downside is the slightly visible disturbance to skies, water and smooth highlight areas of images. The effect is only slight and only the website presentation previews, the original files are not digitally fingerprinted and as such are clean, hi-res images.