A typical 40-inch diagonal plasma or large LCD display in a 16:9 width-to-height ratio provides a surface viewing area of approximately 800 square inches (depending on manufacturer) or about 20 times the viewing area of the nine-inch diagonal monitor. Plasma screens in sizes of 50- and 60-inch diagonal are common today for public messaging, marketing and formal presentation applications. A typical 50-inch diagonal plasma display increases the available image viewing area to more than 1,000 square inches, and the 60-inch provides more than 1,600. At present, flat-panel LCD monitors are available in up to 45-inch diagonal. Fifty- and 60-inch monitors will soon be available.
One must keep in mind, however, that these calculations do not represent a direct correlation between standard CCTV imaging in a 3:4 aspect ratio and the 16:9 aspect ratio of many larger flat-panel displays. By incorporating standard audio-visual industry presentation techniques, an outboard LCD or DLP projection device and front or rear projection screen can be used to produce image sizes that are virtually unlimited. With the wide-angle lenses and light-path-folding mirrors available today, large image sizes projected in relatively small areas are certainly possible.
Video walls, using individually sealed LCD and DLP projection cubes, can be arranged in vertical and horizontal stacked configurations to adapt to the size or space constraints of an existing building or security command center. These cube displays are available in diagonal screen sizes from 40 inches to 70 inches, and when constructed in a stacked configuration, can produce a nearly mullion-less single large screen array in multiple sizes. Several manufacturers now offer units with mullion surrounds measuring as little as 0.5mm in thickness. These larger image-producing cube displays are commonly used in many 911 tactical analysis centers and 24/7 emergency alert centers. They are enabling users to expedite emergency situation awareness and improve action resolution.
All About Space Saving
Do we need images that large in a typical security center? Certainly not. What we do need, however, is the means to display numerous images in the smallest physical area possible. With the video processing components available today it is relatively simple to simultaneously display numerous camera and computer data images on a single large display device.
Security system CCTV integrators have been doing this for years with quad video processors and larger CRT monitors. Now we are not only able to incorporate computer data information into this same equation, but we can mix and match CCTV video camera and computer data information as multiple images in two, four, eight, 16 and more individual images on a single, large screen. We are also able to resize and reposition these images within the screen in real time.
It is possible to display 16 typical CCTV images on a single 42-inch diagonal display device in much the same size as was the standard in the security industry. Although the usable width of the 16:9 format would not be completely filled using nine-inch diagonal images in a 4:3 ratio, a plasma or LCD device can be made to expand the format ratio to make use of the full 16:9 image area available.
Looking at this situation using typical rack-mounted CRT monitors and taking into account the exterior dimensions, a total area to adapt 16, nine-inch images would require 1,600 square inches of physical space, or 48 standard EIA units. The overall equivalent using the larger plasma or LCD display equates to slightly more than 1,000 square inches, or approximately 64 percent less surface space for the same image display area. Using fewer of the larger display devices in lieu of many smaller screens clearly presents significant space savings. It also provides the additional benefits of reduced overall heat generation and power loads.
Image size is not the only parameter to consider as you decide whether to use these display technologies. Resolution, brightness and contrast must also be considered in context of the images to be displayed and the environment in which they are to be displayed.
A typical plasma or LCD flat-panel display may have the capability to display an XGA (1024 x 768 pixels) graphics-standard computer signal. When displaying multiple images on the same display, each image would share the total available number of pixels, thereby reducing the overall number of pixels available for each image. As a result, the images will not be reproduced with the same clarity or sharpness that they would if they were displayed in their native resolution as the only image on the display.