If you have been following our series about video, we are going to discuss some of the important facts and details about brightness, what those numbers mean and image size. If you have not seen our earlier posts, may we recommend you catch up by looking at the past few months!
Lumens and NITS are units of measure of light. Lumens are for video projectors and NITS are for video displays and televisions.
Let’s look at projectors first. Video projector brightness is measured in lumens…or to be a little more specific, in ANSI (American National Standards Institute) lumens. A little history here. ANSI was founded in 1918 and is headquartered in Washington, DC. Simply put, many manufacturers worldwide voluntarily adhere to these U.S. standards for the purpose of apples to apples comparisons.
One ANSI lumen equals the amount of light that a typical birthday cake-sized candle (yes, a birthday cake-sized candle) gives off in a one square-foot area. Video projector ANSI lumen ratings vary from as low as 600 for a dark home theater to as high as 60,000 for an IMAX projector. Some typical recommendations for commercial presentation projector brightness are:
- Small room with the lights off, 2,500 ANSI lumens,
- Medium-sized room, up to 50 people with some ambient light, 3,500 ANSI lumens,
- Larger room for as many as 150 people with some ambient light, 4,500 ANSI lumens,
- The same larger room with the lights on, 6,000 ANSI lumens or more.
A video display’s light output is measured in NITS. The closest we could come to the acronym definition is the Latin word nitere (to shine). A NIT is the amount of light output equal to one candela per square meter. To keep it simple, a candela is a different unit of measurement than a candle, and in comparison, one NIT is almost 3.5 times as bright as a lumen.
A typical commercial display (say 40 inches) used in a huddle-space will have a brightness of 400 NITS. In comparison, a high-brightness 55-inch commercial display used for digital signage in a well-lit space will have as many as 2000 NITS!
Here’s a quick comparison between video projectors and video displays:
- 400 NITS is equal to about 1,350 ANSI lumens
- 1000 NITS is equal to about 3,350 ANSI lumens
- 2000 NITS is equal to about 6,650 ANSI lumens.
Whether you choose a video projector or video display, in most applications, the higher the number the better. This is because you can always adjust the brightness down if it’s too bright, but (and it’s a BIG but), you cannot raise the brightness to more than what it is rated!
We also want to discuss image size. This is a critical aspect that must be determined in advance of your choice of device, be it video projector or video display. After you determine the brightness, you must determine the size. This is typically measured diagonally from corner to corner of the image.
Not to generalize too much, but typically for a general presentation with some text, you divide the image’s distance from the furthest viewer by six. This gives you the screen height.
As an example: for a 20-foot distance you would want the screen height to be 40 inches. For a 16:9 format image, that will translate to about an 80-inch diagonal image (that’s more than 7.5 feet!). FYI, this calculation changes if you are viewing images requiring detailed inspection.
Brightness and image size go hand-in-hand! If you have the right brightness but the wrong-size image, you won’t be able to read the numbers on your Excel spreadsheet. And vice versa. If you have the right image size and the wrong brightness, the image will be washed out and again you won’t be able to read the numbers on your Excel spreadsheet.
Don’t worry though, we can help. Whether you are in the design phase and just have drawings for a space you are building or already have a space where you want to add or upgrade your video system, our team of specialized audiovisual engineers will design a video display system that will match your needs and exceed your expectations, guaranteed!
If you would like to discuss your video system needs, please e-mail email@example.com.