Digital Cameras Essay Research Paper Overview

Digital Cameras Essay, Research Paper

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.

A

Thousand Points of Light: How Digital Images Are Formed

Digital cameras come in several formats designed for the

specialized needs of photographers. They range from inexpensive snapshot

models to sophisticated scanner backs that fit on professional large format

film cameras. Regardless of their size or sophistication, all digital

cameras operate in much the same way.

All images we perceive are formed from optical light energy.

Even digital images created within a computer are eventually converted

into light energy that we can see. In order for a digital camera to store

an optical image, it must be converted into digital information.

A digital camera gathers light energy through a lens,

and focuses it on a CCD which converts it into electrical impulses. These

signals are fed into a microprocessor where they are sampled and transformed

into digital information. This numerical data is then stored, and usually

transferred later on to a computer where the image can be viewed and manipulated.

Black-and-White

Basics

A black-and-white photograph is composed of a wide range

of tonal variations. Like the spectrum of natural light it represents,

the photo’s tones are continuous and unbroken. By contrast, a black-and-white

digital image consists of myriad points of light sampled from the light

spectrum. A digital image’s range of tone is determined by the camera’s

capacity

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