LED displays have been widely applied across various industries, making them familiar and accessible to an increasing number of users. To judge the image quality of displays and select cost-effective products that fit your demands, you need to master the fundamental technical indicators of LED displays and evaluate their quality grades primarily from two dimensions: functionality and performance.
Starting with the functionality of LED displays, their core function is to present diverse content including texts, images and videos to audiences. The most critical capability is true-to-life content reproduction, which relies on high color rendition of the display. The following key technical indicators determine its rendition performance.
How to Identify the Quality Grade of LED Displays
1. Brightness
Brightness delivers an intuitive visual experience that can be distinguished at a glance. However, higher brightness does not always equal better performance; the optimal brightness depends on the application environment and viewing distance.
Indoor LED displays: Around 1,000 nits is ideal
Outdoor LED displays: Over 6,000 nits
Semi-outdoor LED displays: 2,500–5,000 nits
Fine-pitch LED displays: Require lower brightness, roughly 100–300 nits
In short, under the premise that audiences can view clear images under different lighting conditions, long-time viewing shall not cause eye stinging discomfort.
2. Color Temperature
If the colors displayed deviate drastically from the original source material, the screen suffers severe color distortion, which is closely tied to the white balance color temperature.
For direct naked-eye viewing: White balance color temperature of 6,500–8,000K is suitable
For studio broadcast use: The screen’s actual color temperature shall be calibrated to around 5,500K, so images captured and broadcast by cameras can retain authentic colors.
3. Viewing Angle
For display devices, a wider viewing angle is preferable, as it expands the available viewing range. Viewing angles consist of horizontal and vertical angles:
Indoor full-color LED displays: Horizontal viewing angle over 140°, vertical viewing angle over 100°
Outdoor full-color LED displays: Horizontal viewing angle over 100°, vertical viewing angle over 90°
Within the rated viewing range, images must remain complete and clear without color shift when viewed from any angle. This performance is determined by the packaging arrangement of RGB chips inside SMD LEDs; two mainstream arrangements are available on the market: triangular layout and vertical linear layout.
4. Gray Scale
Poor image layering and pixel loss compared with original materials indicate a low gray scale, which fails to reproduce content with full clarity and authenticity. Gray scale strips serve as a professional test tool to directly evaluate gray scale performance. The industry mainstream reaches 16-bit gray scale, with 18-bit gray scale to be widely adopted in the future.
5. Refresh Rate
Flickering visible to the naked eye and horizontal dark bands captured by cameras or camcorders signal insufficient refresh rate.
For direct naked-eye viewing: The minimum refresh rate shall not be lower than 300Hz
For shooting and broadcasting with video equipment: The refresh rate must reach 2,000Hz or above to eliminate scanning lines.
6. Contrast Ratio
A washed-out, hazy picture with a thin fog-like overlay and poor transparency points to low contrast ratio, which must not fall below 1000:1. Contrast ratio is mainly affected by LED packaging technology and module mask design. LEDs with black brackets deliver far higher contrast ratio than those with white brackets.