Image quality is important for any outdoor board, and it’s especially true for digital displays. The density of the LEDs is a critical component, but there are several other factors you should consider as you compare your options: 1. color depth, 2. color calibration, 3. brightness control and 4. viewing angle.
1. Color depth of A LED Display: When all three LEDs (red, green and blue) are at 100% power, white is produced. When all three LEDs are off, the board displays black. In between, there are as many as 281 trillion colors. To make any of those colors in the spectrum the LEDs are shaded in tiny increments. Color palettes that are too limited (anything less than four-trillion colors) result in images that look “cartoonish” and fake. There isn’t enough nuance in the color palette to create realistic images. Be on the look-out for manufacturers that don’t make their color palette easily accessible in their marketing materials. Some LED signs can have color palettes as low as 16 million colors, which is completely inadequate for billboard displays.
2. Color calibration of A LED Screen: LEDs are manufactured in bin codes. These bin codes group LEDs in approximate matches for color. Lesser manufacturers rely only on bin coding for color-match in their billboards. Better manufacturers first use bin codes as the initial matching criterion, but take the extra step to color calibrate (usually at the module level). Premier manufacturers, however, invest the necessary time and money to develop color calibration at the “whole sign” level. This process involves assembling the billboard prior to shipping and using sophisticated camera equipment to color-calibrate the entire board as a unit. This step ensures that images on the board are extremely smooth, with no patchwork, quilted effect.
3. Brightness control for A Digital Billboards: On a sunny day, a digital board has a typical luminance of 5,000 – 7,500 nits (candelas per square meter) and may run at 100% brightness. At dusk and dawn, only 4 - 15% of the power level may be required (between 300 – 1,125 nits) for optimal viewing. The best digital boards have a built-in brightness control that adjusts to maximize visibility – whether it’s day or night, cloudy and overcast or bright and sunny. Brightness control can be managed with both hardware and software solutions.
4. Viewing angle of A LED Display: The viewing angle measures how bright an LED image looks at a given angle. Keep in mind that the brightness will diminish as the viewing angle increases. Your digital board should have a maximum viewing angle of 140° to assure that viewers will be able to see and read the board even as they pass it on the highway.