ABSTRACT
In order to be able to process images by computers, images must first be made available in digital format. In a conventional camera, objects in a scene are focused by the optical elements on to a film, which is placed at the focal plane of the lens. The object is imaged onto the film when it is exposed to light from the object. In a digital camera, an array of photosensitive electronic sensors takes the place of the film. When the sensors are exposed to light, each sensor element develops an electrical charge that is proportional to the number of photons falling on the sensor. This electrical charge is then converted to a decimal number represented in a binary format. Figure 4-1 illustrates the principle of imaging an object. The process of image acquisition consists of focusing the object onto the sensor array by optical means, exposing the sensors to the focused object, scanning the sensor array, and converting the analog electrical signal to digital format. This chapter discusses the methods used in the acquisition process. Current technology uses sensors made out of semiconductor materials, called charge-coupled devices (CCD). So, we will describe CCD sensors. We will also describe briefly the mathematics behind the sampling process and its implications. Finally we will introduce the equipments used in converting film into video format for digital cinema application.
