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Overview
Digital cameras capture images electronically and convert them
into digital data that can be stored and manipulated by a
computer.
Like conventional cameras, digital cameras have a lens, aperture,
and shutter, but they don't use film. When light passes through
the lens it is focused on a photo-sensitive electronic chip
called a charged coupling device (CCD). The CCD converts light
impulses into electrical impulses (also called analog signal
forms). The signals are fed into a microprocessor and transformed
into digital information. This process is called digitization.
Although digital images do not yet match the quality of pictures
produced on film, they represent an enormously flexible medium.
Photographers are no longer limited by the physical properties
of chemistry and optics. Computers outfitted with the appropriate
software can augment and transform images in ways never before
imagined.
History
The origins of digital cameras are intimately
linked with the evolution of television in the 1940s and 50s,
and the development of computer imaging by NASA
in the 1960s.
Before the advent of the video tape recorder
(VTR), television images were optically displayed on monitors
and then filmed by motion picture cameras. Because film and
television technologies were essentially incompatible, Kinescopes,
or "kinnys" as they were called, produced inferior images.
A breakthrough occurred in 1951 when Bing Crosby
Laboratories introduced the VTR, a technology specifically
designed to record television images. Television cameras convert
light waves into electronic impulses, and the VTR records
these impulses onto magnetic tape. Perfected in 1956 by the
Ampex Corporation, video
tape recording produced clear, crisp and nearly flawless images.
The use of VTRs soon revolutionized the television industry.
The next great leap forward happened in the
early 1960s as NASA geared up for the Apollo Lunar Exploration
Program. As a precursor to landing humans on the moon, NASA
sent out a series of probes to map the lunar surface. The
Ranger missions relied on video cameras outfitted with transmitters
that broadcast analog signals. These weak transmissions were
plagued by interference from natural radio sources like the
Sun. Conventional television receivers could not transform
them into coherent images.
Researchers at NASA's Jet Propulsion Laboratory (JPL) developed
ways to "clean" and enhance analog signals by processing them
through computers. Signals were analyzed by a computer and
converted into numerical or digital information. In this way,
unwanted interference could be removed, while critical data
could be enhanced. By the time of the Ranger 7 mission, JPL
was producing crystal clear images of the moon's surface.
The age of digital imaging had dawned.
Since that time, probes outfitted with digital
imagers have explored the boundaries of our solar system.
The orbiting Hubble telescope, a hybrid of optical and
digital technology, maps the limits of the known universe.
Here on earth, digital techniques gave rise
to a host of medical imaging devices, from improved X-ray
imaging in the late 1960s, to Magnetic
Resonance Imaging and Positron
Emission Tomography in the '80s and '90s.
Copyright © 1994-99 Jones International and
Jones Digital Century. All rights reserved.
Bibliography
Books
Baxes, Gregory, Digital Image Processing: Principles
& Applications, New York: John Wiley & Sons, Inc.,
1994.
Brown, Les, Les Brown's Encyclopedia of Television:
Third Edition, Detroit: Gale Research, 1992.
Grotta, Sally Wiener, and Grotta, Daniel, Digital
Imaging for Visual Artists, New York: Windcrest/McGraw-Hill,
1994.
Katz, Ephraim, The Film Encyclopedia:Second
Edition, New York: Harper Perennial, 1994.
Articles
Baig, Edward C., "Smile—You're on Candid
Computer," Business Week, 4 November 1996.
Diehl, Stanford, "Byte's Video Workshop," Byte,
May 1995.
Joch, Alan, "Beyond Hollywood," Byte, May 1995.
Lu, Cary, "Digital Cameras on the Move," MacWorld,
June 1996.
McNamara, Michael J.,"New Imaging, Today &
Tomorrow: 3 New Digital Cameras," Popular Photography, August
1996.
Wiener, Leonard, "Camcorders Go Pro," U.S. News
& World Report, 25 November 1996.
Zuckerman, Jim, "Digital Portraits," Petersen's
Photographic, September 1996.
Credits
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--WebSite Design by Gerhard Wiegand
--the crew
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