The digital camera conceals remarkable technological innovations that affect the formation of the image, the color representation or automated measurements and settings. ** From photon to pixel photon ** describes the device both from the point of view of the physics of the phenomena involved, as technical components and software it uses. Based on the perceptual properties of the visual system as well as on standard transmission and representation, analyzes the solutions to meet the demands of the photographer on the development, contrast, white balance or stabilization of image. The advanced architectures adopted in mobile phones and developments of computational photography are also presented, foreshadowing the features of the future device.