The principle and necessity of nonlinear correction
The video signal is designed to meet the lighting and electrical characteristics of the TV, which can be played on TV or on the monitor. If the TV signal is not corrected, it will cause serious color distortion. Therefore, we must carry on the non-linear gamma correction to the input video signal front end, the corrected chroma space will have the obvious improvement. LED corresponding to the big screen, physical brightness and gray value is proportional to, if not corrected, obviously can not meet the requirements of the color reduction, in particular: low order gray brightness jump, and high order gray naked eye didn't know. As everyone knows, the human eye to light feeling is nonlinear, weak light intensity, doubled, enhanced more than one times the human eye feeling; strong light, light intensity is doubled, increased less than double eyes felt, so the need for the brightness of the nonlinear processing, make eye feel gray change uniform. Therefore, in order to ensure the integrity of the LED large screen color reduction, must be carried out anti gamma correction, after correction, so that its electrical and optical conversion characteristics similar to CRT. The experimental results show that the gray scale correction of the display screen will appear clear texture, strong sense of hierarchy, soft, light and smooth transition.
Gamma is a key parameter of digital image display, LED display and so on in the system, the human eye has a nonlinear response to brightness, only 18% of the brightness of the light source, the human eye is about half of the brightness. The brightness in the CIE (International Commission on illumination) the definition is a region that emits light. How much is a sense of brightness, not a fixed target can be measured. The human eye can distinguish about 80 brightness levels, in a certain environment, the brightness is less than one percent the maximum brightness of objects, the human eye is unable to feel.
The relationship between the physical equipment of light intensity and the applied signal is not linear. The brightness of the traditional CRT is a power function, signal voltage of Y=X 2.5, Y X represents the input signal representing the brightness, the index of 2.5 is usually referred to the Gamma value. The purpose of nonlinear correction is to restore the intensity of light to the human eye, because the nonlinear response of the human eye is exactly the opposite of the nonlinear curve of CRT.
In video systems, gamma correction by the linear optical signal is converted into a video signal and nonlinear, in order to adapt to the conversion of the CRT curve, to achieve the perfect image reproduction, when used directly through the LED display no input signal of two gamma when the correction, due to differences in LED/CRT electric optical conversion curve, cause the whole picture of the performance for contrast disorders, color saturation declines.
Because the human eye to light feeling is nonlinear, and the characteristic curve of LED is linear, so we must adjust the transformation function of LED display, another reason is the Gamma transform function to adjust the inherent characteristics of CCD camera is 0.45, the image is through the CRT value of Gamma correction, about 2.2-2.5, national television standard slightly different. When the value of Gamma is less than 1, the picture will be contrast, showing a lack of sense of hierarchy.
The advantages of the nonlinear correction of the light control system:
Nonlinear 1 pointwise variable correction curve:
In LED display system based on intrinsic characteristics, according to the different light tube, different temperature, different video source to design different nonlinear calibration curve, we display is always in the best working state.
2 stronger color reduction ability:
Market is usually 8 LED display system, this system is a 8 bit RGB input signals (RGB), the output is discrete RGB 8 bit or 10 bit signal. In a typical 8 bit system, 0 is black, the other is white, and the other is between 1 and 255 colors. In digital systems such as LED, if the Gamma value is 3, the lower gray range, the number of visible colors is reduced, and many similar gray levels are merged. That is, a range of input signals are placed on the same output value. The color of this kind of loss does not show up in the CRT, because the CRT signal is simulated, there are countless levels from 0 to 255. Obviously, in order to better restore the original image in the LED display system, the system must have a greater depth of data processing capabilities.
In order to adapt to the needs of technology development, while protecting the user's largest investment yjg own SinoPix control system can support a maximum to 16 bit grayscale processing capability, the input signal can not only perfect performance in 8, and when the input source is 10 or 12, every detail there is enough space to reproduce the original image.
3 high contrast
Vision light SinoPix16 display system can make each LED does have 65536 layers of colour contrast, the brightest and most dark can reach 65535:1. This display has enough space to represent the level of color, and the image looks layered
4 leading lossless grayscale brightness regulation
Brightness competition regulation is usually obtained at the expense of the color level of yjg SinoPix system because of its own system wide enough, with enough space to adjust the brightness to adjust the brightness, even if the maximum brightness of 1 / 64, each color still has 4096 gray, adjusted to the use of various occasions.
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