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what is LED display brightness, grey scale and out of control rate?

what is LED display brightness, grey scale and out of control rate?

what is LED display brightness, grey scale and out of control rate?

Currently the domestic LED display in the factory will be aging (roasted machine), the LED lights out of control pixels will be replaced, "the whole screen pixel out of control rate" control in 1/104, the "regional pixel out of control" control In 3/104 is no problem, and even some individual manufacturers of enterprise standards require factory does not allow out of control pixels, but this is bound to increase the manufacturer's manufacturing and maintenance costs and extend the shipping time. In different applications, the actual rate of pixel out of control requirements can have a greater difference, in general, LED display for video playback, index control requirements within the 1/104 is acceptable, but also can be achieved; If used for simple character information release, the indicator requirements within the control of 12/104 is reasonable.

Brightness discrimination level

Brightness discrimination level refers to the human eye can distinguish the image from the black to white between the brightness level. As mentioned earlier, some of the high gray-scale display, you can reach 256 or even 1024 level. But because the human eye sensitivity to brightness is limited, cannot fully identify the gray level. Which means that a lot of adjacent grayscale grading may look the same. And the ability to distinguish between different eyes. For the display, the human eye to identify the level of nature is the better, because the display image is, after all, to see. The more the brightness level the human eye can tell, the greater the color space of the display means, the greater the potential for rich colors. Brightness level can be used to identify special software to test, the general display can reach 20 or more even if the level is better.

Pixel out of control rate

Pixel out of control rate is the ratio of the minimum imaging unit (pixel) of the display screen is not working properly (out of control). And pixels out of control there are two modes: First, the blind spot, which is blind, when it needs bright, it is not bright, called the blind point; the second is always bright spots, when it needs not bright but it has been lit, Called the regular bright spot. In general, the composition of the pixels are 2R1G1B (2 red, 1 green and 1 blue light, the same below), 1R1G1B, 2R1G, 3R6G, etc., and out of control is generally not the same pixel in the red, Green, blue lights all out of control at the same time, but as long as one of the lights out of control, we think that this pixel out of control. For simplicity, we according to the LED display of the primary colors (ie, red, green, blue) were out of control of the statistics and calculation of pixels, whichever is the maximum value of the screen pixel rate of control.
The number of pixels out of control the total number of pixels than the full screen ratio, we call the "full screen pixel out of control rate." In addition, in order to avoid the loss of control pixels concentrated in a certain area, we propose the "region pixel out of control rate", that is, 100 × 100 pixel area, the number of pixels out of control and the total number of regional pixels (ie 10000) ratio. This indicator on the "General Specification for LED display" SJ / T11141-2003 "out of control pixels are discrete distribution" requirements were quantified, convenient and intuitive.

Grayscale is the so-called color or gray scale, refers to the brightness of light and shade. For digital display technology, grayscale is the number of display color determinants. Generally speaking, the higher the gray level, the richer the color display, the more delicate the picture, the easier the performance of rich details.  

Gray scale depends on the system's A / D conversion bits. Of course, the system's video processing chip, memory and transmission systems must provide the appropriate number of bits of support. The current domestic LED display mainly 8-bit processing system, that is 256 (28) -level gray. Simple to understand that there are 256 kinds of brightness changes from black to white. RGB primary colors can be used to form 256 × 256 × 256 = 16777216 kinds of colors. Which is commonly referred to as 16 million colors. International brand display mainly 10-bit processing system, that is 1024 gray, RGB primary colors can constitute 1.07 billion colors.
Although gray is the deciding factor in determining the number of colors, but not to say that the greater the better. Because the first resolution of the human eye is limited, and then increase the number of system processing system will involve video processing, storage, transmission, scanning and other aspects of the change, the cost of dramatic increases, cost-effective decline. In general, commercial or commercial-grade products can be used 8-bit system, broadcast-level products can be 10-bit system.

Gray - scale non - linear transformation

Gray-scale non-linear transformation refers to the gray-scale data in accordance with empirical data or a certain non-linear relationship between the transformation and then provided to the display screen. As the LED is a linear device, with the traditional display of non-linear display characteristics. In order to enable LED display can meet the traditional data source without loss of gray level, generally in the LED display system after the level will do the non-linear transformation of the gray scale data, the number of bits of data after transformation will increase (to ensure that no loss of gray data). Now some of the control system supplier of the so-called 4096 gray-scale or 16384-level gray or higher after the non-linear transformation is the size of the gray space. 4096 is the use of 8-bit source to 12-bit non-linear transformation technology, 16384 level is the use of 8-bit to 16-bit nonlinear transformation technology. By the 8-bit source to do the nonlinear transformation, the conversion space is certainly larger than the 8-bit source. Generally at least 10. As the same gray, this parameter is not the bigger the better, generally 12 can do enough to change.

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