- This information is reprinted from “Why Do I Look Like A Raccoon?,” and was provided by ITRIX, Inc. For more information, contact ITRIX at 415-957-1744
Copyright© ITRIX, Inc.

The following information deals with specific issues relating to improving the appearance of a videoconferencing room. However, there generally is a conflict of interest between this goal and the design constrictions of the setting in which it is to be accomplished.

In other words, videoconferencing is about turning offices, classrooms, universities, hospitals, and courtrooms into interactive television studios. Aside from the networking intricacies, this poses several challenges to creating a good environment for videoconferencing.

In order to render an image of good quality, a videoconferencing facility must offer light of the right level, angle, and color temperature. There must be enough light to provide a "noise-free" picture (lack of fine-grained static in the displayed image) with adequate depth and focus, and it must come from the proper direction to avoid undesirable facial shadows. Lighting must also enhance image depth and contours by intentionally creating desirable shadows and highlights. In addition, particular care must be given to the tonality of color that will be visible in the room, in regards to how it will affect the auto-iris function of your particular camera.

When implementing these changes to your new videoconferencing room, the room(s) should not contain any "obtrusive" elements that would sacrifice the visual integrity of the rest of the "non-video" rooms. Also, the users should not be made to feel like they are "on stage."

Types of Light
Incandescent Lamps
An incandescent light bulb is the conventional lamp used in most residential and many commercial and industrial lighting applications.

Incandescent bulbs at high wattage are often found in traditional stage lighting, and produce the best results for shooting video because of the favorable way in which the emit red, green, and blue light in relation to the camera. Remember that white light is not the absence of color, but a combination of colors.

However, they are not the best choice for video-conferencing rooms, office, classroom, or hospital environments, for two main reasons:

• Incandescent lights are very hot.
  
  
• Incandescent lights draw more power (which costs more), and the bulbs need to be changed more often their fluorescent counterparts.

A confined space (such as a videoconferencing room) will quickly heat up with just a few high-power incandescent bulbs.

Fluorescent Lamps
The term "fluorescence" describes the phenomenon in which certain materials produce visible light when exposed to electromagnetic radiation.

Fluorescent bulbs are the light of choice in most buildings simply because they are cheap and cool. Fluorescent light is the least preferred light by video and photography professionals for the following reasons:

• The amount of light put out is not great enough
  
  
• Unless a fluorescent fixture has a special ballast (power supply), it will flicker. Although not generally noticeable to the human eye, the flicker is visible to the camera (just as a standard computer monitor's refresh rate can be seen on television) and does affect your codec (coder/decoder) performance
  
  
• The color value/ temperature (the output of red, green, and blue light) is not consistent enough to render a high quality image

Halogen Lamps
Halogen lamps are a type of incandescent light that contains chemicals called halogens in the gas fill.

For the same reasons mentioned regarding incandescent light, halogen lamps are not the best choice for lighting a "closed-in room" because they get very hot and they draw excessive amounts of power.

Characteristics of Light
The larger the surface area of your light source, the "softer" it will be.

Hard light casts a dark shadow that has a well-defined sharp edge. When hard light is used to illuminate a face, imperfections in the skin stand out. The result is less than flattering. It can be generalized that most bright light sources, emanating from a small source will be "hard."

Soft light (diffused) has the opposite effect of hard light, especially when lighting angles are also controlled. A skylight is an example of a soft light.

Brightness and Contrast
Brightness is the perceived intensity of light that reaches our eyes.

Contrast helps us distinguish shapes, edges, and details on the surface of objects. It is the ratio between the brightest and the darkest tone in a scene. In most circumstances, contrast will help clarify an image. Keep in mind that our eyes see a contrast ratio of 1:200 where the video camera can only sees a ratio of 1:5. If the contrast in your image greater than that, the tone above or below will go completely black or white.

Amount of Light
Light intensity is measured in foot-candles (FC). One foot-candle offers illumination equal to the amount of direct light thrown by one candle, one foot away, on a square foot of surface. Higher light, or foot-candle, levels reduce "noise" in the video signal (which appears as fine-grained static in the displayed image).

The drop ceilings commonly found in most office suites are nine feet high. With the usual fluorescent fixtures, the average foot-candle reading taken 4.5 feet from the ceiling will be between 12 and 30 foot-candles.

Points of reference:

• sunlight on an average day ranges from 3000v to 10,000 FC
  
  
• TV studios are lit at about 150 FC
  
  
• a bright office has about 35 FC of illumination
  
  
• moonlight represents about 0.01 FC

Optimal foot-candles for videoconferencing are between 40-60 FC.

Angle of Light
Most soon-to-be-videoconferencing rooms probably have lighting similar to one of those illustrated in Figure 1.

FIGURE 1

Direct LIghting: flourescent luminaire with prismatic lens The flourescent luminaire fitted with a prismatic lens is the most common and least expensive office light fixture. Direct LIghting: flourescent luminaire with prismatic lens The flourescent luminaire fitted with a prismatic lens is the most common and least expensive office light fixture. Inirect LIghting: The flourescent luminaire fitted with a prismatic lens is the most common and least expensive office light fixture.

Most conference rooms have direct overhead fixtures that direct light straight down on the surface of the conference table and the participants head. This causes the undesirable facial shadows (dark eye sockets shaded areas under chins and noses) and excessive highlights.

Uplighting, is the best choice. It essentially uses the ceiling to create a giant "soft box" effect. With enough power, this style of light can render the foot-candles necessary to create a better picture.

However, the drawback is that the light is so uniform, that it winds up hurting the contrast and creates a two dimensional looking image instead of a three-dimensional image.

A Special Note Regarding Track Lighting
Track lighting, although excellent for enhancing the effect of good lighting, has several problems, when used as the main source.

The small bright cans create light that is too hard. Shadows are sharp and prominent, especially on the walls or white-board behind a participant.

Bright track lighting is uncomfortable to look at, and will cause some people to squint.

Color of Light
When professionals discuss room lighting color, they talk in terms of a light's temperature, which is measured in degrees Kelvin (K). The whiter the light, the higher the temperature; lower temperatures take on a reddish cast. Color temperature does not affect the brightness of the light.

Optimum color temperature of light varies between each camera or video system. The majority of video systems will perform best using 3200k. If the room appears particularly greenish/yellow, 5500K bulbs will work best.

Solutions
In an effort to alleviate some of he problems mentioned above, specialized lighting systems have been developed especially for videocon-ferencing needs. By incorporating increased power supply, full-spectrum color, diffused panels, and properly angled placement, these systems can create optimum lighting environments.

For more information, visit ITRIX online at http://www.itrix.com