Display application of HDR technology on small-pitch LED displays

With the maturity of LED display small-pixel pitch technology and the arrival of the 4K display era, the requirement for HDR in terminal displays has become an urgent need. Especially in the image quality restoration, deep color, high brightness and low grayscale display of small dot pitch LED displays, because HDR technology can make small dot pitch LED displays display better effects and more realistic images.

01 Small spacing LED screen system connection
67 mm, 1.5 mm, 1.2 mm, etc. Because the distance between lamp bead points becomes smaller, the number of lamp beads in each box increases exponentially, which requires more receiving cards to drive LED lamp beads on a conventional box. The box has two, three or even four cards (receiving cards).

At the same time, the screen refresh in the LED system control software is also different from the conventional screen refresh method (as shown in Figure 3), because each network cable can only carry 650,000 pixels, so it can only be routed vertically ( As shown in Figure 4), the bandwidth problem of a single network cable can be solved.

It can be seen from the network connections in Figure 3 and Figure 4 that for an LED display with the same physical area, the ordinary LED screen uses 3 network cables, while the small-pitch LED uses 5 network cables to carry the load, and it is a single vertical Traces.

It can be seen from the network connections in Figure 3 and Figure 4 that for an LED display with the same physical area, the ordinary LED screen uses 3 network cables, while the small-pitch LED uses 5 network cables to carry the load, and it is a single vertical Traces.
02 Implementation of LED screen HDR display
There are currently two ways to implement HDR on LED screens: using a video processor that supports HDR function to achieve HDR effect display, and using a sending card that supports HDR function to achieve HDR effect display. Currently, these two methods are in use. The following is a detailed analysis of these two solutions.

Using a video processor that supports HDR function to achieve LED screen HDR display effect is shown in Figure 5:
1.According to the requirements of the HDR ecological chain, an HDR video source is first needed. No matter what HDR standard it is, the film source is a must.
2.The HDR video source enters the video processor, and the video processor decodes the HDR video source. Currently, most HDR video sources are 4K videos.After the video processor decodes the video, it needs to split the image into multiple spliced images.
3.The spliced picture is output to the sending card. The sending card is encoded and then transmitted to the receiving card. The receiving card decodes and drives the LED screen.
This method is that the video processor completes HDR video decoding and processing, and the sending card system is only responsible for encoding, transmission and display, so that the focus of HDR display is on the video processor.

Using a sending card that supports HDR function to achieve LED screen HDR display effect is shown in Figure 6:
1.The HDR video source is directly sent to the sending card system, and the sending card decodes the HDR source;
2.After the video is decoded, it is re-encoded again, and the encoding method is specially marked as HDR video encoding;
3.The encoded data with special markings is transmitted to the receiving card. The receiving card receives the data and uses HDR to drive the LED display based on the encoded data with special markings.
The implementation of this HDR display method is completed using the sending card and the receiving card.