We live in a time when we are party to n amazing range of digital imagery. In the past, images were trustworthy source, but today’s technology has has put paid to this confidence.
Doctored photos and digital imagery are landing on our doorstep with increasing frequency. Just think of the fashion models on the covers of magassines, the images used in advertising, political campaigning, not to mention the music industry. Recently, digital forensics has improved and has begun to regain some confidence in such things. This site provides a brief overview of some of these technologies.
Digital watermarking has been suggested as a means by which images can be authenticated However, a watermark must be included when the photo is taken, limiting this to cameras with this facility.
Passive tools for image authentification can also be useful. These assume that even though digital forgeries may leave few visual clues, they may change the under-lying stats of an image.
These tools can be roughly grouped into five categories: 1) pixel-based, 2) format-based, 3) camera lens, sensor, or on-chip postprocessing; 4) physical techniques that explicitly model and detect anomalies.
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