Since its invention over a hundred years ago, photography has totally
transformed how we perceive our world. It wouldn't be an exaggeration to
say that the camera is one of the most important inventions in all
human history. Photography has made it possible for humans to "see"
objects that are actually thousands of kilometers away.
At their
most basic level, Cameras, both the Single Lens Reflex Camera and
Digital Camera simply involve using a curved piece of glass or plastic
(lens) to conduct a beam of light bouncing off an object, and to
redirect this light in such a way that a real image is formed-an image
that looks exactly like the object in front of the lens. The only
difference between manual or conventional film cameras and digital
cameras lies in how these basic processes are accomplished.
In
film cameras, after the lens has formed an image of the object, the
image is then focused on and recorded by a chemically-coated piece of
plastic, the film. Then the film is chemically processed, after which
the image is printed onto a photographic paper, and then we have
pictures that can then be stored in our photo album or distributed to
friends as desired. But digital cameras take a shorter route to achieve
the same result stated above.
How Digital Cameras Work
Digital
cameras are a part of a larger breakthrough that we've witnessed in
consumer electronics over the past twenty years-the wholesale conversion
of analog information into digital information. When we really get down
to it, CDs, HDTV, DVDs, MP3s, DVR, etc are all built around the
principle of converting fluctuating waves into bits of ones and zeros.
Conventional cameras depend fully on chemical and mechanical
processes-you can actually operate them without electricity! But the
digital camera presents a paradigm shift here: it has a built-in
computer that records images electronically, and must thus be powered by
electricity.
Just like manual cameras, digital cameras also use
the lens-actually series of lenses-to focus the light from an object to
form an image. But unlike the manual camera, the image formed by the
lens in a digital camera is not focused onto a piece of film to be
recorded. Instead, the image is focused onto a semiconductor device that
is capable of recording light electronically. A computer is then used
to break down this electronically-recorded information into digital bits
of data. Let's now take a closer look into the inner workings of a
digital camera.
The Technology
Included in a digital
camera's built-in computer is a sensor that converts light into
electrons, or electrical charges. Depending on the camera's
manufacturer, this image sensor may be either a Charge Coupled Device,
(CCD), or Complementary Metal Oxide Semiconductor (CMOS). To be honest,
notable differences exist between these two types of sensors (i.e. CCD
and CMOS). But they perform the same basic function in a digital
camera-converting light into electricity. Hence, for the purpose of
understanding how a digital camera works, we're going to think of them
as identical devices.
And somewhat like the film cameras, a
digital camera also has to control the amount of light that reaches the
sensor. Yes, it also makes use of the Aperture and Shutter Speed. But
these are mostly automatic and can be reset electronically. Now, a
digital image is just a long string of 0s and 1s. It is the sensor that
reads and interprets the values of these digits as contained in the
cells of each recorded image.
Next, another device known as
Analog -to-Digital Converter (ADC) turns each recorded pattern of light
(pixel values) into digital value by measuring the amount of charge at
each cell, and converting that measurement to binary form. Remember we
stated earlier that every digital camera has an in-built computer? Now, a
processor therein interpolates the data from the different pixels to
form natural color. For the majority of digital cameras equipped with
LCDs, it is possible at this stage to see the image that has just been
photographed before deciding to print it.
At this stage the
information is stored in some form of memory within the camera-all
digital cameras are equipped with a number of storage systems, most of
it removable storage devices. We can consider these as forms of
reusable, digital films. And because pictures take up lots of storage
space, most digital cameras use some sort of data compression to make
the files smaller. A card reader can then be used to transfer the
information stored therein (i.e. photographic images) to a computer for
further usage.
The processes described above sure sound
complicated, right? Don't worry. In practice, it all happens so
effortlessly that we barely take note of anything while using a digital
camera-which is what makes it fun to use: the ease and the speed.
Imagine that you want to e-mail a picture to a friend. With conventional
cameras, you'll first have to capture the image, process the film,
print the picture, and then use a scanner to capture the picture again
and record it as pixel values for onward e-mailing to your loved one.
But with a digital camera, the picture is automatically broken down and
recorded as pixels ready for e-mailing. That's the fun. Plus, you also
get to view the image, live, before setting to print!
Thus,
despite the comparatively better quality of film pictures, digital
cameras will continue to get more and more popular. Also, as digital
imaging technology continues to improve in leaps and bounds, it'd be
interesting to see what becomes of the conventional film camera.
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