1. Test methods and conditions of small-pitch LED display
(1) Equipment: 1 Blu-ray HD player with 1080P (1920×1080 full frame) resolution; 1 high-performance computer with 1080P HDMI output; 1 video signal distributor with 1 to 4 component color difference output.
(2) Test standard video sources, pictures, etc.: blue light source disk; professional test video Hi-Definition Reference (select multiple scenes); DisplayX, SJ/T 11281-2007 "Light Emitting Diode (LED) Display Test Method" standard Test software; computer-generated 1080P standard color scale, full chromatographic gradient, gray scale, and pictures from the Internet, the pictures captured or generated by the above 2 items, etc., the night view of the highway bridge.
(3) Test method: Before the formal evaluation, each manufacturer is allowed to conduct multiple on-site debugging on its own LED\large screen (due to the size of the venue, it is recommended to test the resolution 720P or 1080P line of the splicing screen) to achieve their respective products. The best results. Starting at the specified time, a review team composed of experts with rich experience in image transmission, video display, and LED large-screen hardware will conduct practical application effects evaluation.
2. Evaluation requirements for small-pitch LED displays
(1) Grayscale image test
①The test of gray scale and color scale has always been an important index reference for large screens such as DLP/plasma/LCD/LED or spliced large screens, used to evaluate the large screen splicing and the grayscale transition ability of the controller (if any), and Black and white conversion capability, etc. The more obvious the contrast, the stronger the display system's ability to process color images.
The bidirectional grayscale signal is used to test the number of 16 grayscale levels that the system should display at least. 3 points can be distinguished for each level; 1 point is reduced if the resolution is less than one level, and the lowest point is 0 for this item.
The 25 +2 level gray scale map must be able to distinguish the darkest 3 gray scales A, B, C and the brightest 3 gray scales U, V, W on the screen at the same time. A, B, and C must have layers and cannot look black; similarly, U, V, and W must also have layers and cannot look white. During playback, the large-screen image with any color/color cast should be deducted. If there is no color difference (black and white impure and with other colors), 2 points will be added. If there is color cast, 1 to 2 points will be deducted as appropriate.
②Comprehensive test of sharpness and gray scale. This scene is used to comprehensively test the line number, grayscale, geometric distortion and other performance of the entire system. Under 1080P (1920×1080), each gray level and line number should be clearly distinguishable. At the same time, it can also test the black and white purity of gray. One point is reduced by 1 point if there is a problem; the minimum is 1 point.
③Grayscale real scene picture. The more black and white levels are displayed, the better the ability to reflect the system's gray level processing. The minimum is 2 points and the maximum is 5 points.
(2) Color picture test
①Comprehensive test of dark part of color picture. This scene is a night scene, which focuses on the intensity changes of color shading and halo, and is used to test the color, grayscale, detail display and other performance of the system. 4 points can be clearly distinguished between the boat on the left under the bridge, the halo at the top of the main tower and the bridge deck cables. Depending on the severity of the problem, 1 to 2 points will be deducted as appropriate. If there is no problem in distinguishing between light and dark changes in other details, an additional 1 point will be added.
②Bright detail test: a test of the ability to restore details with bright white as the keynote. This scene is a dining table and dressing table with relatively high brightness. The main test system is to test the reduction ability of the white part under high light and the dynamic range of grayscale. The texture details of window curtains, cloth, brushes and other objects should be preserved intact. All items are in line with 5 points. If there is any non-compliance, 0.5 points will be deducted for each item, and a total of 2 points can be deducted.
③Clarity test of face details. This scene is a close-up static picture of a girl and flowers, reflecting the fidelity of the large-screen splicing system to various details such as facial skin color and spots, and the realness of skin color. The total score is 5 points. If the facial details are not clear, 0.5 points will be deducted. If the facial color is not pure, 1 point will be deducted.
④Color reduction test. Mainly test the color uniformity and white purity. It is very important to restore the various ingredients in the kitchen and the color of the fruits, the pure white crystals on the tray and the barrel of the colored pencils, the wood grain part, the grassland, and the clouds. For impure white color, 1 to 3 points will be deducted as appropriate. The full score is 5 points.
⑤Color saturation and detail test. The edge fluff of the pile ball should be clearly visible, and the texture of the spool and the cloth should be clearly distinguishable. Full score is 5. 1 point is deducted if the fluff is not clear; 1 point is deducted for unclear spool texture; 1 point is deducted if the texture of the cushion cloth is not clear.
(3) Dynamic scene test
Waves and reefs (ROCK&WAVE, Blu-ray video source: 00014. m2ts). This scene is a sea reef scene, used to test the image quality of the device with a large number of small motions under a static background, especially the white balance and detail resolution. In addition, the Fog (water mist) generated by the waves at the 20-27s playback point should be clearly distinguished. Five points are full marks. If the level of waves and reefs is not clear, 0.1 to 1 points will be deducted as appropriate. If the FOG is not clearly displayed, 0.5 to 2 points will be deducted as appropriate.
① Light and dark detail test (Tokyo Night, Blu-ray video source: 00019. m2ts). This scene is a moving image of Tokyo's night scene, which is mainly divided into 4 scenes: the tower under the light; the Christmas tree with embedded lights; the night scene of the bridge and both sides; the night scene around the Ferris wheel. The main test system is the color reproduction ability and the dynamic range of light and dark contrast during dynamic video playback, the mesh details in the bright neon lights, the details of the Christmas tree, the details of the dark parts on both sides of the bridge, the bright parts of the Ferris wheel and the dark parts of the block should be fully preserved. The minimum score is 2 points and the maximum is 5 points (for each item with unclear details and levels, 0.1 to 1 points will be deducted as appropriate).
② Black and white contrast test (Black&White, Blu-ray video source: 00020.m2ts). Mainly test the edge discrimination ability of black and white scenes and black and white people dressed in black and white. The highest score is 5, and the black background can be clearly distinguished from the edge of the black clothes, and 3 points are awarded. If the white background and the edge of the white clothes can be clearly distinguished, 2 points are awarded. If the edges of the same color are unclear, 1 to 2 points will be deducted as appropriate.
③Color expressiveness: accessories (Accessory, blue light test source: 00021. m2ts). The main scenes are flowers and ornaments (necklaces, gloves, feather ornaments, etc.), which mainly test the permeability of colors and the texture of the objects. In addition, the detail display of the tiny floating feathers is also very important. The highest 5 points, if the flower level is not enough, 1 point will be deducted; if the feather details are not clear, 1 point will be deducted; if the color is not transparent, 1 point will be deducted.
④Dark part detail test (Black Image blue light test source: 00027. m2ts). The more black and white levels are displayed, the better the ability of the system to process dark details, and the higher the number of gray levels that can be displayed and restored. The black level is clearly distinguished, get a full score of 10; the black part has insufficient levels, 2-6 points will be deducted as appropriate.
The rest of the tests will not be repeated.
(4) Professional software testing (DisplayX series)
①Pure colors: Black, RGB, P (purple), Y, C (cyan), White. Black and white and 6 colors are displayed in pure colors, the overall color is uneven, the total deduction is 0 to 1 points, compared with the same period. If there are dead pixels, 2 to 3 points will be deducted depending on the number of dead pixels, compared with the same period last year. Maximum 5 points.
②Color and gray scale: gradient test (no polarization). The R/G/B three-color signal with chromaticity gradient from the left to the right and the Y/Purple/Cyan after the two-color mixing are used to test the chromaticity and grayscale changes of the system. The gradual change has no sense of steps, that is, the smoother the transition, indicating the higher the gray level of the system. If the colors are gradually transparent, and there are no faults and vertical steps, the full score is 5 for this item. Depending on the severity of each color, 1 to 3 points will be deducted compared to the same period last year.
③Full-color gradient. The full chromatogram is gradual and has no polarization changes. The brighter and transparent the color, the better. If there are more steps in each color, the more unsatisfactory. Points must be deducted in the evaluation; the closer the display of each color is to the vertical, it proves the grayscale of each color. The better the sense of synchronization of changes. If the gradient is transparent, there are no faults and vertical steps, this item is 4 points. If there is no uneven color change during the gradual change, this item will get another 1 point. Depending on the severity of color tomography, 1 to 3 points will be deducted from the same period.
