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Thomas Edison (right) works on a film camera with George Eastman.


The process of using light-sensitive materials or digital devices to make a permanent visible image (a photograph) of an object. Traditional photographs depended upon the light sensitivity of silver halide deposited in a thin layer of gelatin on paper, glass, or film. When exposed to light in a camera or other photographic instrument, an undeveloped image forms in the silver. The image is made visible in development with a chemical solution and then made permanent by fixing with another solution. Depending upon the kind of photograph, the image may be negative (where light and dark are reversed) or positive (which looks like the original view photographed). Newer photographs use digital cameras and/or computers and printers to make the photograph. The history of photography dates from the early work of Louis Daguerre and others in the mid-nineteenth century. In 1889, photography came into popular use after George Eastman marketed the Kodak camera, which used flexible transparent film. Motion-picture photography dates from 1890, when Thomas Edison built a device to expose Eastman’s roll film in a continuous strip. Digital cameras and video camcorders use electronic means to capture an image and display it on a screen or print a photo on paper.