Once, photo retouching was a tricky craft skill involving darkrooms, scalpels and paintbrushes. Today, it is so easy to do on a computer that all kinds of inappropriate people are having a go. Since March, the Photoshop Disasters weblog (photoshopdisasters.blogspot.com) has been collecting amusing examples of retouching gone bad.

– Fake wars Perhaps the most famous Photoshop disaster occurred last July, when an Iranian news agency released photographs of four missiles supposedly being launched. Photoshop geeks immediately spotted that one of the missile trails had been crudely added in Photoshop. The original picture eventually surfaced, showing one missile sitting in its launcher.

– Freaks Because Photoshop is so easy to use, people get carried away with moving arms and legs and swapping bodies. Photoshop Disasters’ “inadvertent amputation” category is full of one-legged models and missing belly buttons. Three-handed celebrities are also surprisingly common.