What is the relationship between the grayscale and brightness of LED displays?
Tags: led, displays, brightness
Published: 2024-06-18 08:21:10

[LED displays](https://sostron.com/products/) play an important role in modern advertising, entertainment, and information dissemination. Understanding the relationship between its grayscale and brightness is essential for optimizing display effects. 

![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/miocbs0vv0uubbwz4eb4.png)
Definition of grayscale and brightness

Grayscale (also known as brightness) refers to the brightness of each pixel on the display. When displaying images or animations, the brightness of each LED light-emitting diode that makes up the pixel needs to be finely adjusted. The fineness of this adjustment is usually called the grayscale level. The grayscale level can be 16, 32, 64, etc. Through this grading process, the image transmission is clearer. [What should I do if the LED display cannot load an image? ](https://sostron.com/led-display-loading-image-how-to-do/)

Methods for controlling grayscale

There are two main methods for controlling the grayscale of LEDs:

Changing the current flowing through the LED:

The brightness of the LED is changed by adjusting the current flowing through the LED. Generally, the operating current of the LED is about 20 mA. Except for the red LED, whose brightness is not completely proportional to the current due to saturation, the brightness of other color LEDs is basically proportional to the current flowing. [Provide you with knowledge about nit brightness. ](https://sostron.com/knowledge-of-nit-brightness/)

![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/r8usx5fnukvgvl8up0mt.png)
Pulse Width Modulation (PWM):

Use the visual inertia of the human eye to achieve grayscale control by quickly switching LEDs. The PWM method periodically changes the width of the light pulse (i.e., the duty cycle). When the refresh frequency is high enough, the human eye will not perceive the change in brightness. Since PWM is more suitable for digital control, this method is widely used in modern LED displays to achieve grayscale control.

LED control system

The control system of the LED display usually consists of a main control box, a scanning board, and a display control device:

Main control box: obtains the brightness data of various colors of screen pixels from the computer's display card, and then distributes the data to several scanning boards.
Scanning board: Each scanning board controls several rows or columns of LEDs on the display screen, and transmits control signals in serial mode.
Display control device: specifically executes the instructions for lighting or extinguishing each LED.

![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/qra6ibdefnn02q5id5d7.png)
Serial transmission of display control signals

There are currently two main ways to transmit display control signals serially:

Centralized control of the grayscale of each pixel:

The scanning board decomposes the grayscale value of each row of pixels from the main control box (i.e., pulse width modulation), and then transmits it serially to the corresponding LED in the form of pulses (1 for lighting and 0 for non-lighting). This method uses fewer devices, but the data transmission volume is large. At 16 levels of grayscale, each pixel requires 16 pulses; at 256 levels of grayscale, 256 pulses are required. Due to the limitation of the operating frequency of the device, this method can generally only achieve 16 levels of grayscale. [Introduce the pixel density and resolution of LED display screens. ](https://sostron.com/pixel-density-and-resolution-of-led-display/)

![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/9qz7rswlzu3jrm980kv6.png)
Pulse width modulation:

The scanning board transmits the 8-bit binary grayscale value of each LED, and each LED has its own pulse width modulator to control the lighting time. At 16 levels of grayscale, each pixel only needs 4 pulses; at 256 levels of grayscale, only 8 pulses are required, which greatly reduces the transmission frequency. Using this decentralized method of controlling LED grayscale, 256-level grayscale control can be easily achieved.

![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/d3dsk2fie36e8l0sumu0.png)
Summary

The grayscale and brightness of LED display screens are closely related. By adjusting the grayscale level, the brightness can be accurately controlled. Changing the current flowing through and pulse width modulation are the two main control methods. Among them, PWM is widely used in modern LED display screens because it is more suitable for digital control. Understanding and applying these control methods can significantly improve the image quality and visual effects of LED display screens.

![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/01w8es62j4874bjf11k6.png)
Thank you for watching. I hope we can solve your problems. Sostron is a professional [LED display manufacturer](https://sostron.com/about-us/). We provide all kinds of displays, display leasing and display solutions around the world. If you want to know: [Analysis of LED display screens used in command centers.](https://dev.to/sostrondylan/analysis-of-led-display-screens-used-in-command-centers-3kj4) Please click read.

Follow me! Take you to know more about led display knowledge.

Contact us on WhatsApp：https://api.whatsapp.com/send?phone=+8613570218702&text=Hello