A qualified and able to withstand the test of the small-pitch LED display must undergo rigorous testing before leaving the factory. After it is officially delivered to the customer, it can guarantee long-term normal operation and a good display failure rate is greatly reduced.
1. Test methods and conditions for small-pitch LED displays
(1) Equipment: 1 set of 1080P (1920×1080 full frame) resolution Blu-ray HD player; 1 high-performance computer with 1080P HDMI output; 1 1 video signal distributor with 4 component color difference output.
(2) Standard video source and test pictures: blue light source disk; professional test video HD reference (select multiple scenes); DisplayX, SJ/T 11281-2007 "Light Emitting Diode (LED) Display Test Method" standard test software; computer generated The 1080P standard color gradient, full chromatographic gradient, grayscale and pictures from the Internet, the above 2 intercepted or generated pictures, etc., the night view of the highway bridge.
(3) Test method: Before the formal evaluation, each manufacturer is allowed to splice its own large-screen LED (due to the size of the website, it is recommended to test the resolution of the spliced screen 720P or 1080P line) to perform multiple on-site debugging to achieve their respective product. The best result. At the beginning of the specified time, some experts with rich experience in image transmission, video display and LED large screen hardware will form a review team to evaluate the actual application results.
2. Evaluation requirements for small-pitch LED displays
(1) Gray image test
1Grayscale, gradient test has always been an important indicator reference for large screens or large screens (such as DLP/plasma/LCD/LED), used to evaluate large screen splicing and grayscale conversion capabilities of the controller (if any), as well as black and white conversion Ability etc. The more obvious the contrast, the stronger the ability of the display system to process color images.
The two-way gray signal is used to test the 16 gray levels that the system should display at least. Each level can distinguish 3 points; less than 1 level reduces 1 point, this item has at least 0 points.
25 +2 grayscale image must be able to distinguish the darkest 3 gray levels A, B and C, and the brightest 3 gray levels U, V and W on the screen. A, B and C must have layers, not It looks black. Similarly, U, V, and W must have layers and cannot appear to be white. During playback, any large-screen images with color/color cast should be deducted. If there is no color difference (black and white are not pure, there are other colors), please add 2 points. If there is a color deviation, please deduct 1~2 points as appropriate.
2Comprehensive test of definition and gray scale. This program is used to comprehensively test the performance of the entire system, such as the number of lines, grayscale and geometric distortion. In 1080P (1920×1080), each gray level and line number should be clearly distinguishable, and the black and white purity of gray can also be tested. 1 point reduction is problematic; at least 1 point.
3 gray scale real map. The more black and white levels displayed, the stronger the ability to reflect the system's grayscale 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, focusing on the intensity changes of color shading and halo, and is used to test the system's color, grayscale, detail display and other performance. 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 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 up to 2 points can be deducted.
③Face detail clarity test. This scene is a close-up static picture of a girl and flowers, reflecting the fidelity of the large-screen stitching 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 and fruit colors in the kitchen, the pure white crystals on the tray and the barrels of colored pencils, the wood grain parts, and the grasslands and 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 coral reefs (ROCK&WAVE, Blu-ray video source: 00014.m2ts). This scene is a coral reef scene used to test the image quality of a device that contains a lot of small movements in a static background, especially white balance and detail resolution. In addition, the fog (water mist) generated by the wave at the playback position of 20 to 27 seconds should be clearly distinguished. 5 is a perfect score. The level of waves and coral reefs is not clear, so the deduction should be 0.1 to 1 point. FOG is not clearly shown, and the deduction is appropriate 0.5 to 2 points.
1 light and dark detail test (Tokyo night, Blu-ray video source: 00019.m2ts). The scene is a moving image of the night view of Tokyo. It is divided into four scenes: under the lighthouse; the Christmas tree embedded under the lights; the bridges and night scenes on both sides; and the night scenes 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 details of moiré fringes in high-light neon lights, the details of Christmas trees, the details of the dark side of the bridge, and the highlights should completely retain the dark details of the Ferris wheel and the block . The minimum is 2 points and the maximum is 5 points (each detail and level are not clear, each deducts 0.1 to 1 point).
2 Black and white contrast test (black and white, Blu-ray video source: 00020.m2ts). It mainly tests the edge resolution of black and white scenes and black and white costumed characters. Maximum 5 points, black background and black clothes edges can be clearly distinguished, get 3 points. The white background and the edge of the white dress can be clearly distinguished and score 2 points. If the edges of the same color are not clear, please deduct 1 to 2 points as needed.
3-color expressiveness: jewelry (accessories, blue light test source: 00021. m2ts). The main scenes are flowers, jewelry (necklaces, gloves, feather jewelry, etc.), mainly to test the transparency of colors and the texture of objects. In addition, the details of the feathers are also very important. At most 5 points, if the level of the flower is not enough, 1 point will be deducted; if the feather details are not clear, 1 point will be deducted; if the color is opaque, 1 point will be deducted.
4Dark part detail test (black image blue light test source: 00027.m2ts). The more black and white levels displayed, the stronger the system's ability to process shadow details, and the higher the number of gray levels that can be displayed. The black level is clearly distinguished, and the score is 10 points; the black part is not enough, and the deduction is appropriate 2 to 6 points.
The remaining tests are not described.
(4) Professional software testing (DisplayX series)
1 Pure colors: black, RGB, P (purple), Y, C (cyan), white. Black and white and 6-color pure color display, the overall color is uneven, the total deduction is 0~1 points, compared with the same year. There is a dead pixel, the number of dead pixels is 2 to 3 points, compared with the same period of the previous year. Maximum 5 points.
2 Color and gray: gradient test (no polarization). The R/G/B three-color signal of chromaticity from left to right and the Y/purple/cyan after two colors are used to test the chromaticity and grayscale changes of the system. The gradient has no sense of steps, that is, the transition is smoother, indicating that the gray level of the system is higher. The color gradient is transparent, there are no defects and vertical steps. This score is 5 points. The color of each color is determined according to the severity, and the comparison is 1 to 3 points.
3 full-color gradients. The chromatographic gradient is saturated, there is no polarization change, the brighter the color, the better the transparency. If the bars of each color have more steps, the more unsatisfactory, the deduction should be deducted during the evaluation; the closer the color is to the vertical, the proof of each color. The better the sense of synchronization. Gradually transparent, trouble-free and vertical steps, these 4 points. When the gradient changes, there is no color unevenness change, and the item gets another 1 point. The color tomogram depends on the severity, and the comparison is 1 to 3 points.
