DIGITAL CAMERAS

Sidebars


More memory can be worth the added cost.


FoneCam lets you shoot by remote.


Federal managers are buying digital cameras and scanners in record numbers, and the
reason is obvious: Agencies are expanding their use of images in databases, documents and
on Web pages.


After spending a few weeks using two digital cameras, I’m not surprised by their
popularity; the little marvels are a fantastic way to capture digital images.


If your agency or office uses any digital images, you can make a good case for a
digital camera. But even if you don’t use images in your documents, this may be the
technology that makes PC imaging a practical alternative for such tasks as tracking
projects or taking inventories.


Most digital still cameras are best suited for taking a quick photo of an employee or
building, or to record work in progress. Any application that requires VGA or SuperVGA
resolutions is the perfect place to use one of the $1,500-or-less units.


For the cameras I’ve tried, images were well focused and had good color
saturation, fidelity, contrast and sufficient resolution for most uses. They even printed
well on 600-dot-per-inch laser printers.


Over the next few pages, you will get a look at everything from high-end professional
digital cameras that yield images whose quality rivals that of film to inexpensive
snapshot cameras you might try out to see if they have a use in your office.


Although the low-end cameras’ resolution is not up to such tasks as photographing
crime or accident scenes, used in conjunction with film cameras they provide an excellent
way to transmit instant views to a remote office. For example, while you’re using a
film camera to collect evidence or archival records, you can also use a digital still
camera to capture images to a notebook computer for immediate transmission.


Inexpensive 35-mm cameras—even disposable cameras—take higher-resolution
pictures than low-end digital cameras, but that isn’t the point. The point is how
easy it is to use a digital camera and to move images from camera to computer. It
couldn’t be much easier.


The quality and cost of digital cameras with largely similar specifications can vary
widely, mostly as a result of the electronic sensors each uses.


Most cameras use charge-coupled device (CCD) sensors, but the size and configuration of
the sensors varies.


A few use complimentary metal-oxide semiconductor sensors, and you can expect to see
more. CMOS digitizer arrays use less power than CCD sensors and, because they are computer
chips, can do some of the signal processing tasks that CCD cameras must relegate to
additional chips.


The two major CCD types used in today’s cameras are linear, trilinear and area
array CCDs.


Linear arrays are the sensors you see in desktop scanners and fax machines—a
single row of sensors that scan past the image. A trilinear array uses three closely
grouped single linear arrays with color filters.


To capture an image, the linear array in a page scanner moves across the page or, in a
camera, across the image plane. In fax machines and sheet-feed scanners, the paper moves
across the array.


Single-array mechanisms require three passes to capture the three primary colors to
produce a color image.


Triarray mechanisms capture the primary colors in a single pass, providing for shorter
exposure times.


Linear arrays provide the highest resolution and color depth but, because they require
a stable camera platform and image, are used only in higher-end cameras.


Area array sensors are large enough to allow for projection of the entire image on the
screen. By using a beam splitter prism, you can illuminate three screens with a single
image.


But area array sensors are likely to introduce aliasing, an effect that makes straight
lines into staircase or jagged lines.


Area array cameras come as single-shot or multiscan systems. The single-shot sensor
array includes all three color sensors in the single array.


Multiscan or multishot sensors use a single array but switch three filters through the
light for each single image.


Check out the pros and cons


Pros:


No film or developing costs
No wait for developing
Easy file transfer to PCs and applications
Easily adjustable resolution
Ability to delete bad images on the fly
No scanner
Image resolutions match needs
Easy preview of images
Lightweight—even with batteries and AC power
supply
Storage for 40 or more VGA images—perfect for

fast-loading
Web pages


Cons:


Until you get into five-figure digital cameras, which capture images at many millions
of pixels, lens quality is of small importance. More expensive models use glass lenses.
For low-end digital cameras, plastic lenses capture as much information as
lower-resolution images can display. But plastic is disappearing from the optics of even
the cheapest cameras.


Increasing numbers of professional digital cameras are conventional single lens reflex
(SLR) camera bodies with electronic sensors and digital circuitry added. They accept
standard SLR lenses, but, unless users are working at high resolutions, the higher quality
lenses can’t add much, if anything, to the quality of the final digital image. After
all, even a $10 disposable camera can take clear photographs at what would be a high
resolution when compared with most digital images.


At the high end are digital film backs—replacements for the film carriers used by
medium- and large-format cameras. The film backs sometimes lack any storage, as they
connect directly to a computer and use the computer’s hard drive or removable media
drive to store images.


Some digital cameras have internal memory that can store a few images, but most use
removable storage to increase their capacity.


Flash memory cards use a chip that works similarly to EEPROM (Electronically Erasable
Programmable Read Only Memory), as do many newer PC BIOS chips. They can be erased and
rewritten indefinitely and maintain image files even when not powered.


Many digital still cameras use a brand-name flash memory card, such as Epson America
Inc.’s CompactFlash. Flash memory can be written to in blocks; EEPROM only byte by
byte.


To store images, some cameras use Type II PC Cards; Sony’s Mavica uses standard
3'-inch floppy diskettes, making it easy to transfer images to your PC.


At a 70K average file size, a lot of VGA images in .jpg file format fit on an average
hard drive, or even on a 1.44M floppy. Even high-resolution files from low-end cameras are
only about 250K. High-end professional cameras, capable of capturing large-format images
with greater color depth, and at high resolutions, can easily produce files of 10M and
more.


If you connect the camera di-rectly to your PC or to the camera’s AC power supply,
or if you have rechargeable batteries, it costs virtually nothing to make a daily or even
hourly record of projects. Working that way makes it easy and cheap to store the images in
case you ever need them for a report, or to document the process.


For complex, rapidly moving projects such as dissembling a machine or recording an
office move, however, a digital video camera is more appropriate.


Digital video cameras can store more images—thousands rather than dozens of still
images—and offer similar resolution, but the images are more difficult to transfer to
PCs, and the cameras cost much more.


It’s not difficult to imagine a day in the near future when any office that today
has a Polaroid instant camera or a single-use disposable camera on hand for emergencies
would also have a digital still camera and perhaps even a digital video camera.


Most digital cameras—even low-end models—are expensive compared with SLRs.
But prices are dropping.


Chances are, if you wait a few months your favorite camera will either come down in
price or add features.


Sound familiar? Like everyone’s dream-machine PC? As with a PC, buy your digital
camera when the price-performance ratio is acceptable.  


John McCormick



The storage limits of most digital cameras are not carved in
stone.


Most cameras let you add memory—the digital equivalent of
film—in the form of additional or larger removable memory cards.


The memory cards aren’t cheap, but if you’re working in
the field and can’t conveniently upload images to a computer, extra memory and extra
batteries are worth the extra cost.


Prices for extra storage vary widely depending on the type of
memory a camera uses.


Computer Discount Warehouse Computer Centers Inc. sells memory
cards for most cameras.


Capacities listed are megabytes available on formatted cards
rather than image capacity, which depends on the camera and resolution of the image.


The following list details CDW’s prices for single units:


16M—$119
20M—$130
40M—$215
48M—$260
64M—$339
80M—$410
120M—$639


8M—$72
12M—$98
16M—$110
32M—$180
48M—$259


4M—$27
8M—$45
16M—$88


You can contact the Vernon Hills, Ill., company at 800-991-4239,
and check its products on the Web at http://www.cdw.com.



John McCormick, a free-lance writer and computer consultant, has been working with
computers since the early 1960s. 



To take pictures with most digital cameras, you pack ’em up
and take ’em with you. The whole point of the FoneCam from Moonlight Products Inc. of
San Diego, is that you pack it up and don’t take it with you.


The camera was designed to be placed in a classroom, a border
crossing or any remote location you want to photograph regularly. Mount the
unobtrusive—barely larger than a cell phone—FoneCam and plug it into a phone
jack. It has a built-in 14.4-Kbps modem and can share the line with a telephone answering
machine, fax machine or modem.


When you want to take a picture, call it up and give it the
go-ahead or set it up to create a scheduled image log of a site. For multiple views with a
single call, add ExtensionCam.


You can download images as .jpg, .tif, .bmp, .png or .pcx files
to a PC, or post live pictures to the Web.


Control software runs on any PC with Microsoft Windows 95,
Windows 98 or Windows NT, 10M of hard drive space for software and additional space for
image storage, a CD-ROM drive for software installation and a modem.


FoneCam comes with 4M of on-board RAM, a 320- by 320-pixel
charge-coupled device image sensor that supports up to 24-bit color, and a lens with a
focal length ranging from centimeters to infinity.


For more information, check the company’s Web site at http://www.fonecam.com


Contact Moonlight at 619-625-0300.


—Sami Lais



inside gcn

  • artificial intelligence (ktsdesign/Shutterstock.com)

    Machine learning with limited data

Reader Comments

Please post your comments here. Comments are moderated, so they may not appear immediately after submitting. We will not post comments that we consider abusive or off-topic.

Please type the letters/numbers you see above

More from 1105 Public Sector Media Group