Electronic cameras use one of three devices to store
images. These three devices are a 2-inch video floppy
disk, a hard drive or Random-Access Memory (RAM),
and an integrated circuit (IC) card or chip.
In the 198Os, the still-video camera was introduced
in the Navy. The still-video camera uses a 2-inch video
floppy disk capable of recording 50 or 25 images. The
number of images that can be recorded on a floppy disk
depends on whether the image is recorded in the field"
or "frame" mode.
The FlELD MODE uses one track per image on the
floppy disk and allows 50 images to be recorded on one
disk. The field mode provides poorer resolution
because there are less pixels per picture. The FRAME
MODE uses two tracks per image and allows 25 images
to be stored on one floppy disk. The frame mode
provides higher quality because more pixels per image
are recorded.
Still-video cameras use an analog signal to record
the images. This variable waveform represents density
and colors that are created electronically by the intensity
and the color of light striking an image sensor within
the camera. This analog signal is the same type of signal
used to record most motion-video images. It is also the
same type of signal used in conventional television.
Many still-video cameras have a playback capability
and may be connected directly to a television monitor
to view the images.
An analog signal records the lowest resolution of
the electronic cameras, thus using the least amount of
memory per image. Most still-video cameras have a
limited resolution of approximately 380,000 pixels.
A still-video camera used by the Navy is the Sony
Pro Mavica MVC-5000. This camera has three CCD
chips that are used as the image pickup device and the
high-band format to improve resolution.
An important factor to remember is that a still-video
camera is an analog system, not a digital system. The
format and configuration of a still-video floppy disk is
different than that of a computer system, which is
digital. By using the appropriate hardware and
software, you must convert an image captured on a
still-video camera from analog to digital format before
it can be modified or printed in a digital-imaging
system.
Still-Digital Cameras
A still-digital camera is superior to a still-video
camera. As the name implies, a still-digital camera
records an image in digital format. This digital format
uses the binary system of "0s and 1s." The combination
of these digits represents densities and colors created
electronically by the intensity and the color of light
striking an image sensor within the camera.
A digital image has a much higher resolution than
an analog image. This higher resolution provides more
pixels per image, but it also requires much more
memory per image. Digital cameras use an IC card or
chip and RAM or a hard drive. The RAM is built
permanently into the camera and must be downloaded
to another storage device. This storage device is an
internal or external hard drive. This hard drive is similar
to the hard drive found in personal computers. Kodak's
Digital Camera System (DCS) uses a hard drive to store
images.
The Kodak DCS still-digital camera combines a
Nikon F-3 body and a standard lens with a digital-image
back to capture high-resolution color or
black-and-white images. The Nikon body operates
similar to a camera with conventional film. The major
difference between the Nikon being used with film
compared to the DCS back is that the image area of the
DCS is only one half of the size of a 35mm-film frame.
This change in image area affects the effective focal
length. For example, a conventional 35mm lens
becomes a 70mm lens with the DCS. The Nikon F-3
functions, aperture settings, shutter speeds, and light
metering operate the same as with film. Three major
components that make up the Kodak DCS are as
follows: an electronic back, a camera winder, and a
digital storage unit.
Kodak's DCS models have a digital-image back
that contains a 1,280 by 1,024 pixel CCD imager. This
means the CCD is capable of recording about 1.3
million pixels. The color back equates to film speeds
of 200,400, and 800. The monochrome back equates
to film speeds of 400, 800, 1600, and 3200.
With a winder (spooler), you can shoot up to 2.5
images per second. The system has a standard 6
megabyte (Mb) buffer that can store six images in one
burst. Thus it is possible to shoot faster than the images
are stored.
The camera body of the DCS 100 is tethered to a
Digital Storage Unit (DSU) that contains a hard drive.
The 200Mb hard drive can store 158 uncompressed
images or about 600 compressed images. The DSU also
has a key pad for system control and a 4-inch
monochrome monitor so you can view the images
immediately.
3-9

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