The difference and identification of brightness and grayscale of LED display

We often hear that the grayscale and brightness of LED display are what they are. So how much do you know about the grayscale and brightness of LED display? Let's take a look at the explanation given by Shenzhen Kewei Optoelectronics professionals.

The grayscale of LED display is also called color scale or grayscale, which refers to the brightness. For digital display technology, grayscale is the determining factor of the number of displayed colors. Generally speaking, the higher the grayscale, the richer the color displayed by the display screen , the more delicate the picture, and the easier it is to show rich details.

The grayscale level of the LED display mainly depends on the number of bits of the A/D conversion of the system. Of course, the system's video processing chip, memory and transmission system must provide support for the corresponding number of bits. At present, domestic LED displays mainly use 8-bit processing systems, that is, 256 (28) grayscale levels. Simply put, there are 256 brightness changes from black to white. Using the three primary colors of RGB, 256×256×256=16777216 colors can be formed. This is commonly known as 16 trillion colors. International brand displays mainly use 10-bit processing systems, that is, 1024 grayscale levels, and the three primary colors of RGB can form 1.07 billion colors.

Although grayscale is the determining factor for the number of colors, it does not mean that the larger the better. First of all, the resolution of the human eye is limited. Secondly, the increase in the number of system processing bits will involve changes in various links such as system video processing, storage, transmission, scanning, etc., which will increase costs dramatically and reduce cost performance. Generally speaking, civilian or commercial products can use 8-bit systems, and broadcast products can use 10-bit systems.

Brightness identification level

Brightness discrimination level refers to the brightness level of the image that the human eye can distinguish from the blackest to the whitest. As mentioned earlier, the grayscale level of the display screen is very high, which can reach 256 or even 1024 levels. However, due to the limited sensitivity of the human eye to brightness, these grayscale levels cannot be fully recognized. In other words, many adjacent grayscale levels may look the same to the human eye. And the eye's discrimination ability is different for each person. For the display screen, the more levels the human eye can recognize, the better, because the displayed image is for people to see after all. The more brightness levels that the human eye can distinguish, the larger the color space of the display screen, and the greater the potential for displaying rich colors. The brightness discrimination level can be tested with dedicated software . Generally, a display screen that can reach more than 20 levels is considered a relatively good level.

Grayscale Nonlinear Transformation

Grayscale nonlinear transformation refers to transforming grayscale data according to empirical data or some arithmetic nonlinear relationship and then providing it to the display screen for display. Since LED is a linear device, it has different nonlinear display characteristics from traditional displays. In order to make the LED display effect conform to the traditional data source without losing the grayscale level, the nonlinear transformation of grayscale data is generally performed in the back stage of the LED display system, and the number of bits of the transformed data will increase (to ensure that the grayscale data is not lost).

At present, the so-called 4096-level grayscale or 16384-level grayscale or higher by some domestic control system suppliers refers to the size of the grayscale space after nonlinear transformation. 4096-level adopts the nonlinear transformation technology from 8-bit source to 12-bit space, and 16384-level adopts the nonlinear transformation technology from 8-bit to 16-bit. The space after nonlinear transformation from 8-bit source is definitely larger than that of 8-bit source. Generally, it is at least 10 bits. Just like grayscale, this parameter is not the larger the better, and generally 12 bits can do enough transformation.

Therefore, for the grayscale and brightness, the bigger the better is not necessarily true. Instead, depending on customer needs, the appropriate grayscale and brightness will produce unexpected results.