Digital Camera Basics
让我们say you want to take a picture ande-mailit 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 -- orpixels-- that collectively make up the image. (For information on sampling and digital representations of data, seethis explanationof the digitization of sound waves. Digitizinglight wavesworks in a similar way.)
If you want to get a picture into this form, you have two options:
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- You can take a photograph using a conventional filmcamera, process thefilmchemically, print it onto photographic paper and then use adigital scannertosamplethe 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 adigital camera. Just like aconventional 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 asemiconductordevice 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.