The image perception is influenced by the distance between the viewer and the screen. As a rule of thumb the ideal viewing distance is 1.5 x the pixel pitch in meters. So in a 12 mm pixel pitch screen it is 18 meters. At this distance the human eye (or brain) no longer sees individual pixels but the whole picture. Of course you can get closer (and certainly further away) watching the screen. Closer to the screen the pixels will become increasingly evident, but the image will long remain acceptable.
The viewing angle is generally understood, “how far a viewer to either side of a screen can move, and still see the same brightness”. It is often spoken about “readability” while the viewing angle really only has to do with the brightness.
The viewing angles for an LED displays are measured horizontally and vertically, and indicate over what range images on the LED screen are fully visible without the screen displaying a negative image.
The LED industry defines viewing angle as the full angle at which brightness is half of the brightness from dead center. More scientifically, if ø (angle theta) is the angle from off center (0°) where the LED’s brightness is half, then 2ø is defined as the full viewing angle.
The highest the brightness is, the lowest the viewing angle scale will be
The viewing angle of a LED display represents the limit of its optimal picture quality. Sit at a position at a wider angle than that of its viewing angle and you will experience worse picture.
If the viewing angle of the LED screen becomes lower, the LEDscreen brightness will be higher, or vice versa. If the contrast ratio between LED screens’ brightness and environmental brightness is higher, the led screens’ showing performance will be more colorful. But a too high brightness will consume a lot of energy and create high heat. For that the led chip’s brightness decreases much faster, and of course, its lifespan will become shorter.
The visibility angle of a screen is by convention the angle within which the brightness of a display is equal to the 50% of the frontal luminosity.
For example, a LED screen with 5000 NIT frontal luminosity (NIT = millicandels/sq) has a visibility angle equal to the angle by which the brightness is reduced to 2500 NIT. This visibility angle can vary depending on the LED and the technical features of the display.
In conclusion, it can be stated that loss of brightness under viewing angle start with radiation characteristics of individual LEDs. In most cases radiation characteristics of LEDs show 50% brightness level at about 60°.