Résumé : |
'One picture is worth more than a thousand words' is a popular saying which appeared in the 20th century, resembling an earlier quote from the Russian writer Ivan Turgenev in his book Fathers and Sons: "A picture shows me at a glance what it takes dozens of pages of a book to expound." Since the skin is the only human organ fully accessible to visual examination, it explains why photography has become so widely used in dermatology firstly, and then in cosmetology. In the past ten years, all the domains of digital imaging technology have considerably improved : photograph acquisition, image processing, easiness of storage, teleconsultations.
Photography is of utmost importance to cosmetology because it allows looking at visible changes of skin characteristics. Despite the fact that digital cameras are owned by an incredibly large number of people, some important photographic principles are relatively poorly understood by many when it comes to professional utilisation of images. Because digital pictures can easily be manipulated, it is therefore essential for the public to know the basics of photographic methods used to demonstrate and support cosmetic claims, and for professionais to grasp that photographic tests must be carried out in the same way as scientific measurements. As a consequence, traceability, reproducibility, repeatability, and calibration are concepts which also totally apply to photographic methods. The knowledge of the key factors influencing the quality of one picture and the validity of its analysis should allow the development of critical thinking when looking at photographs acquired during clinical studies or at quantitative/qualitative information extracted from them. |