How to calculate the brightness of a sunlight screen?
When many end customers choose a sunlight screen, they often pay attention to its various parameters. One of them is the most concerned by many end customers: the brightness of the sunlight screen, but many manufacturers have different brightness units. What do they mean? How to convert them? What reference value do they have for the performance of the sunlight screen? The following is an analysis for you:
For display devices, brightness is a very critical performance measurement indicator. And brightness is measured in candela per square meter (cd/m2) or nits (nit). Just like the power of a car engine is expressed in “horsepower”, so is nits. It means that the brightness of a display is equivalent to the brightness of how many candles.
The light of a 300 nit desktop display is equivalent to the brightness of 300 candles in a 1 square meter space. A 1500 nit outdoor display is equivalent to the illumination of 1500 candles.
In addition, nits are not the same as ANSI lumens (a common specification in front projection solutions). 1 lumen represents the amount of light reflected by a candle per square meter at a constant distance. Reflected light can be measured in lumens, while direct light is measured in nits.
This is why projectors are usually measured in lumens, while displays (including rear projection) are measured in nits. Sometimes projection installations are measured in foot-lamberts (FL), which is equivalent to 1 lumen per square meter, in order to make brighter rooms produce higher perceived brightness screen reflections. 1 nit is equivalent to about 0.292FL.
Back to the display, in order to measure the brightness of the display, you need to display something on the screen. Usually, the brightness is measured from edge to edge and from top to bottom when the screen is showing a completely white image. For displays that require a backlight, such as LCDs, a full white measurement will tell you the maximum light output that the display can achieve.
Although it is unlikely that you will display a completely white image on the screen, this number represents the highest brightness that the display can achieve.
For self-luminous display devices (such as plasma, OLED or LED screens), brightness calculations are more difficult. Because each pixel is directly addressed (and turned on or off based on what is directed to it), the brightness of each pixel will vary as the power driving the pixel is shared among all the pixels. For example, a full white screen will be measured lower than a small white square in the middle of the screen.
These two situations represent two common indicators, one is standard brightness measurement (i.e. typical value) and the other is peak brightness measurement (i.e. peak value).
It is clear here that if someone asks the question “how bright is this display device”, it is difficult to give a direct answer to him. It depends on the specific measurement, as well as the display technology used, and what is displayed on the screen in sunlight when the measurement is made.
