Copyright theft and possible legislative changes, such as the Orphan Works Bill in the USA, make it ever more important that all online images have copyright and basic contact data embedded in the file. Unfortunately most web site publishers and export for web software strip out such information, which leaves images exposed to copyright theft. It is very easy to download images that appear on web sites and once on someone else's computer, the picture has no link to the photographer or their ownership of the copyright.
There have been many cases of images taken in that way appearing on FlickR or other such content sharing sites or even being used for commercial purposes: sold as prints, part of CD or downloadable collections - in some cases discovered because they were being sold on eBay. Microsoft's IconicBritain competiton also looks dodgy.
Stock photographers rely on selling multiple licences over time of the same image for their income. Once an image is effectively in the public domain it rapidly loses its value especially for, say, advertising, which is where the best licence fees are found. An advertiser is unlikely to use a photograph that has been appearing all over the internet – they want exclusivity to protect their brand values.
No photograph (especially if of usable size; say more than 400 pixels on longest dimension) should leave the photographers control without having embedded at least:
The photographer should ensure a credit is published with images – in most cases they have a legal right to assert their status as creator of the work. This should require any online use to include this data in all images on the website.
This should use the IPTC standard where the data is in the file but does not affect the image. Sidecar files are not appropriate as they do stay with images. It is straightforward process and not at all technical so no excuse.
Most web sites do not embed any copyright or contact data in the image files displayed on their web sites. Many do not watermark larger, more useful, images.They can then be downloaded with a few mouse clicks and it is only the conscience of the downloader that controls what happens to the picture.
Picture management or editing software, including PhotoShop, strips out embedded data when exporting for web use. In the days of dial-up connections everything had to be small; now the few extra bytes of data are neither here nor there.
Photographers will have to pressure their online publishers to ensure that copyright data is in all online image files; not just associated with the image on the web site. Through the bigger publishers, professional bodies and individually software manufacturers should be required to make products not automatically strip data.
At the same time, especially with the orphan works movement in the USA and potentially elsewhere, legislators should make it illegal to strip copyright data out of an image file. After all it is illegal to remove serial numbers from guns, cars and other tangible products. The only reason is for illicit purposes – the same is true for stripping copyright data.
It will not stop the determined but along with education will perhaps make the essentially honest think twice.