LED virtualization production of all aspects of the resolution concept

203 views admin 2023-10-13

In the film virtualization production process based on LED background wall, pixel and resolution have different forms of expression because it involves different technical links such as image acquisition, transmission, processing and display.

Real-time rendering

In the real-time rendering process, the engine renders the 2D image of the virtual scene according to the display requirements of the LED background wall, and outputs the signal to the next processing process. Image resolution in this process is mainly reflected in the "rendering resolution", that is, the number of horizontal pixels and the number of vertical pixels that are set during rendering and need to output the image.

Video signal processing

The video signal processing step receives the image signal rendered by the engine, performs the corresponding technical operation, outputs the signal to the next processing step, and the resolution of this stage is reflected as "processing output resolution", that is, the product of the number of horizontal pixels and the number of vertical pixels set when the image is output. Different from the input image signal, the resolution of the input image can be set higher or lower in the video signal processing, so that the image can be cropped or transformed in the process of processing.

LED background wall display

The LED background wall will display the image after receiving the image signal, and the pixels and resolution of this link are mainly manifested as the "display resolution" and "physical resolution" of the LED background wall. First of all, because the transmitted image itself can exist independently of the display device, when displaying the image, you can set how many pixel units the image has in the concept of horizontal and vertical, and the total number of pixels is the "display resolution". Since the LED background wall is divided into two parts when displaying the inner and outer cones, the "display resolution" can also be specifically divided into "display resolution of the outer cone" and "display resolution of the inner cone". The display resolution of the outer cone is the "processor output resolution", while the display resolution of the inner cone is determined by the real-time area of the inner cone and the pixel density specified by the video processor. Second, because the image needs to rely on the LED background wall display, from the technical realization point of view, the smallest physical unit of the LED background wall is the independent RGB three primary color LED lamp beads, as shown in Figure 6, so the total number of LED background wall lamp beads constitute the background wall "physical resolution", which is also the LED The maximum display resolution that the background wall can support when displaying images. Similarly, the "physical resolution" of the background wall can also be divided into "physical resolution of the outer cone" and "physical resolution of the inner cone". The physical resolution of the outer cone is equivalent to the total number of physical pixels of the whole background wall. The physical resolution of the inner cone is equivalent to the product of the number of horizontal physical pixels and the number of vertical physical pixels in the LED background wall area covered by the inner cone image.

Camera image

The camera imaging process is more complex, requiring the camera to capture the foreground of the actor's performance and The virtual background displayed by the LED background wall obtains the composite image of the visual effect in the camera, and its resolution is reflected in five aspects: the lens resolution of the camera, the physical resolution of the CMOS target surface, the resolution of the setting when shooting, and the original display resolution and the original physical resolution of the visual effect background in the camera. Among them, the lens resolution power, also known as the analytical power, describes the ability of the camera optical lens to distinguish the details of the subject. The physical resolution of the CMOS target surface refers to the total number of transverse and longitudinal physical imaging units (physical pixels) on the target surface of the CMOS image sensor of the camera. The "set resolution" at the time of shooting is the product of the number of horizontal and vertical pixels of the output image set by the camera when shooting. The background of the visual effect inside the camera is the image formed by the LED background wall cone shot by the camera, its original display resolution is equivalent to the "inner cone display resolution" of the LED background wall, its original physical resolution is equivalent to the "inner cone physical resolution" of the LED background wall.