How Digital Cameras Work

In­ the past twenty years, most of the major technological breakthroughs in consumer electronics have really been part of one larger breakthrough. When you get down to it, CDs, DVDs, HDTV, MP3s and DVRs are all built around the same basic process: converting conventional analog information (represented by a fluctuating wave) into digital information (represented by ones and zeros, or bits). This fundamental shift in technology totally changed how we handle visual and audio information -- it completely redefined what is possible.

The digital camera is one of ­the most remarkable instances of this shift because it is so truly different from its predecessor. Conventional cameras depend entirely on chemical and mechanical processes -- you don't even need electricity to operate them. On the other h­and, all digital cameras have a built-in computer, and all of them record images electronically.

The new approach has been enormously successful. Since film still provides better picture quality, digital cameras have not completely replaced conventional cameras. But, as digital imaging technology has improved, digital cameras have rapidly become more popular.

In this article, we'll find out exactly what's going on inside these amazing digital-age devices.

Understanding the Basics
Let's say you want to take a picture and e-mail it to a friend. To do this, you need the image to be represented in the language that computers recognize -- bits and bytes. Essentially, a digital image is just a long string of 1s and 0s that represent all the tiny colored dots -- or pixels -- that collectively make up the image. (For information on sampling and digital representations of data, see this explanation of the digitization of sound waves. Digitizing light waves works in a similar way.)

If you want to get a picture into this form, you have two options:

• You can take a photograph using a conventional film camera, process the film chemically, print it onto photographic paper and then use a digital scanner to sample the print (record the pattern of light as a series of pixel values).

• You can directly sample the original light that bounces off your subject, immediately breaking that light pattern down into a series of pixel values -- in other words, you can use a digital camera.

At its most basic level, this is all there is to a digital camera. Just like a conventional camera, it has a series of lenses that focus light to create an image of a scene. But instead of focusing this light onto a piece of film, it focuses it onto a semiconductor device that records light electronically. A computer then breaks this electronic information down into digital data. All the fun and interesting features of digital cameras come as a direct result of this process.

In the next few sections, we'll find out exactly how the camera does all this.

Cool Facts

• With a 3-megapixel camera, you can take a higher-resolution picture than most computer monitors can display.

• You can use your Web browser to view digital pictures taken using the JPEG format.

• The first consumer-oriented digital cameras were sold by Kodak and Apple in 1994.

• In 1998, Sony inadvertently sold more than 700,000 camcorders with a limited ability to see through clothes.