LED Walls offer many advantages over projection. While they do have a higher up-front cost, they are cheaper to maintain…
Calibration plays a key role in ensuring your LED display looks incredible. When LEDs are manufactured, they generally have a 5nm wavelength tolerance window. Meaning that if the target red color has a wavelength of 700nm, an LED could be 705nm and still be considered within the acceptable range. The acceptable tolerance would actually be 695nm to 705nm, or 10 nm of total potential variance. What does that mean in the real world?
The average person can detect a color shift of about 2.5-3.5nm. Two LEDs that are next to each other where one is 700nm and another that is 703nm will appear, to most people, slightly different. The above range of 10nm presents a problem then, when an LED display that is made up of literally THOUSANDS of these LEDs all have slightly different wavelengths.
Your LED display wall will (or should) undergo a calibration process before they arrive at your facility for install. Generally, this happens at the manufacturer. For example, when you buy an LED display from THOR AV, we setup all the LED panels for your facility and run calibration tests and adjustments on them. When you get LED wall panels from a lesser-known brand, or one that saves $$ by skipping the calibration step, it is very likely that your wall will not be uniform in brightness or color.
BRIGHTNESS CALIBRATION FOR YOUR LED DISPLAY
Let’s examine what it means to calibration your LED display for brightness and color, starting with brightness.
When you see brightness or calibrated brightness on a specification sheet, it is referencing the brightest an LED display can be and still have all the LEDs at a matched brightness. The brightness on an LED is calibrated by turning the brightness on each LED down until they are matched. For example, if one section is measured at 1100 nits (a nit is a measurement of the intensity of visible light) and another section measures 1000 nits, the 1100 nit section will be adjusted to only put out 1000 nits.
The “weakest” LEDs in your display become the maximum calibrated brightness your wall can display. This is another example of the importance of consistency across all the thousands of LEDs in your display.
Additionally, it is not uncommon to see a 10-20% variance in the brightness of LEDs in your display when they are new (well, you shouldn’t see them, the manufacturer should calibrate it for you), only to have that variance increase as your LED display ages. Particularly in LED panels that are mounted higher. Heat is a major factor in LED “depreciation” and since heat rises, the upper panels are affected more.
In most indoor church and venue settings, LED displays run much lower than the maximum brightness. This means that the LED depreciation will be greatly reduces which extends the life of the component. If LED depreciation is a concern for you, rotating your panels from time to time can help reduce LED aging.
LED DISPLAY COLOR CALIBRATION
Calibrating the color of an LED display is a bit trickier that calibrating brightness. A typical conservative sized wall might use 28 LED panels for a video wall and could have between 580K and 900K pixels (or more). Each pixel has three colors, red, green, and blue so now there are 580K red LEDs to match, 580K green LEDs to match and 580K blue LEDs to match. Now add more walls, or more panels? Yikes!
To compensate for all those LEDs which can all have a 5nm variance, there are a few techniques that we can apply. The most common is color mixing. With color mixing we can add a bit of one of the other colors to adjust the color shift, so they are all the same color. By adding a near microscopic amount of “other color”, we can “pull” the color into a tight color tolerance. By doing this, the overall color gamut (total amount of available colors) is reduced, so there is a tradeoff. The more your LEDs are off to start with, the greater a reduction is total available colors you will have.
MAINTAINING THE CALIBRATION OF YOUR LED DISPLAY WALL
Due to the LED depreciation mentioned above, your LED display can shift over time. We recommend that a new LED wall be calibrated before being installed. Then after a year, it’s a good idea to check the calibration again. Setting up a regular maintenance schedule will protect your investment and give your LED display wall the best possible image.
LED DISPLAY CALIBRATION WRAP UP
A good manufacturer and good installation partner are critical to getting the best LED display quality and ongoing support. A reputable company like THOR will ensure that the LEDs in your LED panels start with the best possible matching and have a long-life span. They will calibrate your LED display to look perfect is with the highest potential brightness and the most available colors. Make sure the LED display company you pick is thinking through these things and addressing them so that your investment lives up to its potential.