Digital photography
The process of electronic acquisition, the equivalent of taking
a photograph, is often referred to as image capture.
Light intensity is detected in digital camera by an photosensor.
This is normally a charge-coupled device (CCD), although
beginning to appear in some systems.
When photons strike the sensor, they give up energy.
This causes electrons to be emitted, turning the energy
of the photons into electrical energy.
The number of electrons that are emitted can be measured
to determine how many photons struck the capture element,
and from this the scanner can generate a value for the
intensity of light arriving from the point on the original
being analyzed.
The aim of the digitization stage is to capture all the information
from an original that will be needed in the reproduction and
convert it into an array of binary numbers that a computer can
process. The human visual system actively seeks cues that will
give it information about the objects within the visual field,
and a reproduction of an image that contains a large amount
of detail is almost always preferred to one in which some of
the detail has been lost. The more information that the
reproduction contains about the original scene—the objects
in it, their colors, textures—the more realistic the reproduction
Like conventional cameras, digital cameras come in compact,
single-lens reflex, and large-format varieties. Low-resolution
compacts are useful for producing classified advertisements
and tend to have relatively simple optics, image-sensing
electronics, and controlling software. Digital cameras are
with the addition of CCD backs and storage subsystems.
The capture resolution of these cameras is ideal for news
photography and other applications with similar quality
requirements.
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