Some commercial photographers, and some amateurs interested in artistic photography, have been resistant to using digital rather than film cameras because they believe that the image quality available from a digital camera is still inferior to that available from a film camera, and the quality of images taken on medium format film is near-impossible to match at any price with a digital camera. With the acceptable image quality and the other advantages of digital photography, particularly the time constraints of vital importance to newspapers, the majority of professional news photographers have begun capturing their images with digital cameras. Photography is used to preserve memories of favorite times, to capture special moments, to tell stories, to send messages, and as a source of entertainment. Photography as a usable process goes back to the 1820s with the development of chemical photography. Photography is a unique and creative medium of self-expression. Fine art photography includes photographs made to fulfill a vision, and reproduced to be sold directly to the customer. Landscape photography are photographs of different locations often made to be sold to tourists as prints or postcards. Digital photography was used in astronomy long before its use by the general public and had almost completely displaced photographic plates by the early 1980s. Photography can also be viewed as a commercial and artistic endeavor. "One picture is worth a thousand words," which has an interesting basis in the history of photography. Conceptual photography turns a concept or idea into a photograph.