What are the differences between encryption, visible watermarking and invisible watermarking?
A. Whilst these are all security devices for digital material and the terms are frequently used interchangeably, they are nevertheless three distinctly different protection methods. Encryption works by locking an object file with a ‘key’ and providing that key only to authorised users. Whilst this generally provides a high degree of active security, once an encrypted file is opened, the contents become unprotected and may then be readily edited, copied and disseminated without any further form of control. Visible watermarking usually places a visible mark superimposed onto an image. These watermarks can be removed by image processing software and, for this reason, do not offer any high degree of protection. They are, however, frequently used as a promotional tool for identifying low resolution view files when used as part of a ‘lightbox’ or catalogue of images. Invisible watermarking, sometimes known as fingerprinting or digital steganography, protects image data at a very deep level w
