Digital imaging or digital image acquisition is the creation of a digital representation of the visual characteristics of an object, such as a physical scene or the interior structure of an object. The term is often assumed to imply or include the , , , printing and display of such images. A key advantage of a , versus an analog image such as a film photograph, is the ability to digitally propagate copies of the original subject indefinitely without any loss of image quality. Digital imaging can be classified by the type of electromagnetic radiation or other waves whose variable attenuation, as they pass through or reflect off objects, conveys the information that constitutes the . In all classes of digital imaging, the information is converted by s into digital signals that are processed by a computer and made output as a visible-light image. For example, the medium of visible light allows digital photography (including digital videography) with various kinds of digital cameras (including digital video cameras). X-rays allow digital X-ray imaging (digital radiography, fluoroscopy, and CT), and gamma rays allow digital gamma ray imaging (digital scintigraphy, SPECT, and PET). Sound allows ultrasonography (such as medical ultrasonography) and sonar, and radio waves allow radar. Digital imaging lends itself well to by software, as well as to (including image manipulation). Before digital imaging, the first photograph ever produced, View from the Window at Le Gras, was in 1826 by Frenchman Joseph Nicéphore Niépce. When Joseph was 28, he was discussing with his brother Claude about the possibility of reproducing images with light. His focus on his new innovations began in 1816. He was in fact more interested in creating an engine for a boat. Joseph and his brother focused on that for quite some time and Claude successfully promoted his innovation moving and advancing him to England. Joseph was able to focus on the photograph and finally in 1826, he was able to produce his first photograph of a view through his window.