Thanks to megapixel and standards-based HDTV network cameras, the language used by security professionals has undergone a major change. Instead of scan lines, we talk about resolution and pixels per inch to define the image quality needed for a particular scene. And the vocabulary we use for resolution has changed from CIF, 4CIF and D1 to 720p and 1080p. Instead of volts peak-to-peak, we talk about the advanced compression, processing power and frames per second capabilities of the cameras. But what we often overlook in this image-quality conversation is an equally crucial element of surveillance: the video monitor. If the resolution of the display doesn't match the high-quality of the video being streamed, it affects how operators perceive the area under surveillance and could negatively impact their ability to respond.
Fueled by demand for better image quality, the Society of Motion Picture and Television Engineers (SMTPE) developed the High Definition Television Standard, or HDTV, which the consumer market has overwhelmingly embraced. Over the past two years, the security industry has followed suit, particularly with regards to HDTV network security cameras. Today, video is typically used as a reactive tool. But as users shift emphasis to more proactive risk deterrence, display technologies under development both in the consumer electronics field and through joint development projects between the Department of Defense and academia will most likely come into play.
Over the past decade, television manufactures have been trying to one-up each other to produce displays with ever larger footprints. Dimensions currently top out at 152 inches (it's a plasma TV from Panasonic), but there doesn't seem to be an end in sight as manufacturers continue to push the envelope. There is, however, another battle for supremacy -- one that is focused on image quality and defined in terms like broader range of color, faster response time, increased brightness, and broader fields of view.
Today's HDTV displays are typically manufactured with a 16:9 aspect ratio, and it is an ideal format for large flat-screen video monitors because it coincides with the new wider format streaming from more advanced HDTV-quality cameras. The higher resolution standard delivers the image clarity critical to real-time surveillance and critical for using archived video as an investigative tool or in a criminal prosecution. Furthermore, since these HD displays are now standard, off-the-shelf equipment, security professionals gain the benefit from commodity pricing.
HDTV display technology falls into three categories: Liquid Crystal Display (LCD), Light Emitting Diode (LED), and Plasma, each with its own pros and cons:
- LCD -- Pros: Higher resolution than plasma, no danger of burn-in. Cons: Cannot achieve true black, narrow viewing angle, brightness and color shift when viewed away from screen's sweet spot.
- LED -- Pros: Excellent black levels, low heat emission, substantial energy savings, long lifespan, slim and lightweight design. Cons: Relatively narrow viewing angle.
- Plasma -- Pros: Wide viewing angle, excellent black levels, great for viewing moving images, lower cost. Cons: Potential image burn-in if scene remains static for hours at a time or there is fixed text in the viewing window, brightness fades over time.
But moving forward, one of the most interesting technologies gaining traction is Organic Light Emitting Diode (OLED) which, as its name implies, uses organic compounds sandwiched between two layers of transparent plastic that emit light when an electrical charge is passed through them. In addition to amazingly crisp image quality, OLED displays consume considerably less energy when rendering multi-color images, which greatly reduces their environmental impact. For the security industry, the benefit of OLED displays is similar to that of higher resolution cameras -- namely, clarity. The better the image quality rendered on the display, the more likely it will result in actionable information.