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CHAPTER 1 : BEFORE YOU SHOOT ■
Bridging the Film/Digital Gap
Since many of us remember the world of film (whether as skilled photographers or
point-and-shoot users), it’s comforting that much of the nomenclature of digital pho-
tography is similar. Digital cameras have lenses, f-stops, and shutters just like the old
cameras. Light is captured and recorded. Images are stored and shared. However, it is
important to know that the differences are also great, and if you apply your old knowl-
edge indiscriminately to the digital world, you are likely to get unsatisfactory results or
not fully utilize the capabilities of the new medium. Let’s look at some of the similari-
ties and differences.
Capturing Light: Electronic vs. Chemical
Both digital cameras and film cameras capture and record light. However, film cameras
rely on a chemical process. Silver halide crystals change when struck by light, forming a
latent image that is revealed upon development with a chemical agent. Figure 1.1 sum-
marizes this familiar process.
Figure 1.1: Film is both a capture and a storage device. The image is revealed upon chemical
development.
Digital cameras rely on a much more complex system that includes several inter-
connected electronic components and sophisticated image processing. Let’s look at this
system in more detail.
The Digital Capture and Storage Process
Digital capture starts with the sensor chip. This chip contains an array of photorecep-
tors, each capturing one pixel of the ultimate image. The number of receptors in the
chip is what determines the camera’s maximum resolution. In most systems, a layer of
filters is applied over these receptors (see Figure 1.2), so that each one can capture only
one of the primary colors—red, green, or blue. These colors are the basis of the RGB
color model used in all computer imaging. Electronic processing, either in the camera
or in a computer, then combines these separate R, G, and B values into RGB pixels in
the image.
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