Total Environmental Dynamic Range - the Key to Assuring Maximum Visual Impact in any Venue

A key factor to consider when selecting a projection display is understanding the minimum Total Environmental
Dynamic Range required to achieve killer imagery in the target venue.

The term Total Environmental Dynamic Range (TEDR) describes the actual contrast ratio achieved in a venue,
including the impact of ambient light. Thus, the TEDR value defines the dynamic range, or contrast, the viewers
actually perceive. You will see, even in venues with a minimal amount of ambient light, the TEDR value will be
much lower than the contrast ratio defined in projector specification sheets.

The method of calculating TEDR is relatively simple:

TEDR = Projector Screen Brightness / (Projector Screen Black Level + Ambient Light reflected by the Screen)

The most complicated part of the process is converting the three values in the formula to one standard of measurement. For purposes of this article, we will use Foot Lamberts (FtL). FtL is a measurement that defines the
light being reflected by the screen.

Step 1: Projector Screen Brightness

Convert the lumens produced by the projector to Projector Screen Foot Lamberts (PFL) using the following formula:

PFL = (Projector Lumens / Screen Area in Sq.Ft.) X Screen Gain

Step 2: Projector Black Level

Projector Black Level (PBL) must also be defined in terms of Foot Lamberts. The approximate PBL value can be calculated in terms of lumens, by simply dividing the projector lumen spec by the projector's specified contrast ratio.
As an example, a 1,000 lumen projector with a 1000:1 contrast ratio, in theory, should produce a PBL of 1 lumen.
We then use the same formula we used in step one to convert the lumen-based PBL to a FtL based value (PBFL).

PBFL = (PBL in Lumens / Screen Area in Sq. Ft.) X Screen Gain

Step 3: Ambient Light

For new construction, defining the ambient light that will fall on the screen is best done with the help of the lighting designer. For existing installations, we recommend taking a real-world measurement using an accurate incident light meter positioned where the screen will exist. Hold the meter parallel to the screen surface aimed toward viewers' position. Many luminance meters measure incident light in terms of Lux. If this is the case with your meter, the Lux value will need to be converted to Foot Lamberts.

To convert Lux to Foot lamberts, use the following two formulas:

1. Convert ambient incident Lux to Lumens:

Ambient Incident Lumens = Ambient Incident Lux X Screen Area in Sq. Meters

or

Ambient Incident Lumens = Ambient Incident Lux X (Screen Area in Sq Ft / 10.56)

2. Convert Ambient Incident Lumens to Ambient Incident FtL (AIFL)

AIFL = (Ambient Incident Lumens / Screen Area in Sq.Ft.) X Screen Gain

Step 4: Bringing it All Together

Now that all of our variables are expressed in terms of FtL, we can use the formula to calculate the TEDR
that will be achieved:

Total Environmental Dynamic Range = Projector Foot Lamberts / (Projector Black Level in FtL + Ambient Incident
Light in FtL)

Or, stated in short form, using our acronyms:

TEDR = PFL/(PBFL + AIFL)

Putting Total Environmental Dynamic Range to Work for Your Customers

As an approximate guide, DP recommends Total Environmental Dynamic Range targets for the application categories
listed below:

- Conference Room (PowerPoint, Spreadsheets, some Video or HD): 10-20:1 rear or front-screen
- Home Media and Entertainment (Video, HD, Videogames, Web): at least 15-30:1 rear-screen, 30-50:1 front-screen
- Worship (Hymn Text, IMAG, some Video): 10-20:1 rear-screen, 20-40:1 front-screen
- Staged events and broadcast applications (CG content, Video and HD): 30-50:1
- Theater or screening room (Video, HD, CG content): at least 500-1000:1

Of course, customer preferences and content present additional variables, meaning no simple set of rules will
work for every application. However, as you start to consider TEDR in the systems you design, you will define the TEDR values that work for your customers as well as the projector, screen and lighting configurations that deliver those TEDR values.

It is all about dynamic imagery. The final simple rule: Reduce ambient light as much as possible. If TEDR values are
still too low, bring more lumens to the task and consider the use of high gain and/or rear projection screens.

Tech Tip Archive

Demo Program: Commercial AV - Full Line and Precision Line Dealers:

• Dealers and Special Contractors may purchase up to two demo units per calendar year.
  
• Demo units may be purchased at 5% off of DPI's published end column Commercial AV dealer pricing
  (End Column x .95).
  
• Excluding iVision, which already comes standard with a lens, the 5% demo discount may also be
  applied to (1) projection lens for each demo projector purchased.

• Dealers in good credit standing receive standard payment terms - 2% cash with order, 1% 10 days,
  net 30 days.

Home Cinema Dealers:

• Home Cinema Dealers may purchase (1) demonstration iVision or dVision projection system per calendar
  year at 50% off DPI's published list price. So long as that unit is maintained in the Dealer's demonstration inventory through the end of the calendar year it was purchased, and the dealer retains in their employ at least one technical associate who has received Digital Projection training certification, the Dealer qualifies
  for Elite Home Cinema end column pricing on all additional iVision and dVision projectors purchased through
  the end of the same calendar year.
• Home Cinema Dealers may purchase (1) demonstration Mercury or HIGHlite projection system per calendar year at 50% off DPI's published list price. So long as that unit is maintained in the Dealer's demonstration inventory through the end of the calendar year it was purchased, and the dealer retains in their employ at least one technical associate who has received Digital Projection training certification, the Dealer qualifies
  for Elite Home Cinema end column pricing on all additional Mercury and HIGHlite projectors purchased
  through the end of the same calendar year.
• Home Cinema Dealers may purchase (1) demonstration Reference Display projection system per calendar year at 40% off DPI's published list price. So long as that unit is maintained in the Dealer's demonstration inventory through the end of the calendar year it was purchased, and the dealer retains in their employ at least one technical associate who has received Digital Projection training certification, the Dealer qualifies
  for Elite Home Cinema end column pricing on all additional Reference Display projectors purchased through
  the end of the same calendar year.

Manufacturer's Representatives:

Rich Jackson
ANSR
8430 Enterprise Way, Oakland, CA 94621
510-638-3800

Joe Blacker
Audio Associates
9160 Red Branch Road, Ste.E-5, Columbia, MD 21045
410-964-1212

Eric Leicht
AV Partners
3272 Windflower Circle, Thousand Oaks, CA 91360
805-492-7055

Sharon Culotta
Culotta Communication
247 D Street, Suite 108, San Rafael, CA 94901
408-836-5671

Larry O'Neill
Dobbs Stanford Corporation
2715 Electronic Lane, Dallas, TX 75220
214-350-9009

Kenneth Colson
E.D.A. Sales, Inc.
5815 Live Oak Parkway, Suite 2G, Norcross, GA 30093
770-300-9484

Steve Johnson
HP Marketing Company
7340 South Alton Way, # G, Englewood, CO 80112
303-804-9566

Dan Muckle
Muckle Sales, Inc.
7150 SW Hampton Street, Suite 115, Tigard, OR 97223
503-620-0444

Marla Suttenberg
Sapphire Marketing LLC
1 Kalisa Way, Suite 108, Paramus, NJ 07652
201-576-9490

Frank Weese
Visitec
2020 Dean St - L2A, St. Charles, IL 60174
630-762-0300

November 2004
December 2004