Three people are standing in front of a painting in the museum, each one taking a picture of it. The art student copies it with brush and paint; The professional photographer bans it on the film in its analog camera; The tourist presses on the button of her smartphone. Which of these images is different from the other two?

The art student has to spend more work on her copy; But in a sense the tourist is with the smartphone of cross-country skiers. Color on canvas, just like the bit of exposed film, is a purely physical representation; A chemical flower on a susceptible medium. The image can not exist independently of this physical embodiment. In contrast, the image stored in the smartphone is essentially numeric. In an approximate way, the camera divides its field of view into a grid of tiny cells in the smartphone and stores a set of numerical values ​​which represent the intensity of the colors in each of these cells; These numbers are the ones that are transmitted - in compressed form - when the picture is sent to friends or placed on the Internet.