HD Indoor P3.91 Led Advertising Digital Video Screen Board Rental Price
HD Indoor P3.91 Led Advertising Digital Video Screen Board Rental Price Analyze various color processing technology of LED display First, 3+2 multi-primary color processing method: In the spring, everything recovers. Under the blue sky's rays, the green grass is green; the autumn wheat is...
HD Indoor P3.91 Led Advertising Digital Video Screen Board Rental Price
Analyze various color processing technology of LED display
First, 3+2 multi-primary color processing method:
In the spring, everything recovers. Under the blue sky's rays, the green grass is green; the autumn wheat is rolling; under the sunshine, it is golden. The colorful nature is so beautiful, but unfortunately the existing LED display can not fully reproduce this beautiful scenery. Although LEDs are monochromatic light, LEDs of various colors still have a half-wave width of about 30 to 50 nm, so their color saturation is limited. It can be seen in the figure that the color saturation of LED full-color screens in yellow and cyan regions where color is extremely abundant in nature is seriously insufficient.
In recent years, in the field of flat panel display, it has been keen to discuss 3+3 multi-primary color displays (red, green, blue, yellow, cyan, and violet) to expand the color gamut and reproduce more abundant natural colors. So, can the LED display achieve 3+3 multi-color display?
We know that in the visible light range, yellow and cyan are monochromatic light, and we already have high-saturation yellow and cyan LEDs. Purple is a multicolor light, and single-chip purple LEDs are not present. Although we can not achieve red, green, blue plus yellow, blue, purple 3 + 3 multi-color LED display. However, it is feasible to study red, green, blue, yellow, and blue 3+2 multi-color LED display screens. Since there are a large number of highly saturated yellow and cyan in nature, this study is of some value.
In the current variety of TV standards, the video source is only red, green and blue, and there are no yellow or blue. Then, how does the display yellow and blue primary colors drive?
In fact, in determining the yellow and blue primary colors driving strength; we follow the following three principles:
1, in the increase of color saturation at the same time, can not change the color tone;
2. The purpose of increasing the primary colors of yellow and cyan is to enlarge the color gamut and thereby increase the color saturation. The overall brightness value cannot be changed;
3, with D65 as the center; RYGCB gamut boundaries as the endpoint, in the gamut within each point for linear expansion.
Under the guidance of the above three principles; according to the law of the gravity center, we can find 3+2 multi-primary color processing methods. However, if we really want to achieve 3+2 multi-color full-color screen, we have to overcome the yellow, cyan LED brightness is insufficient; cost increases and other difficulties, is currently limited to theoretical discussions.
Second, the color reproduction process:
The birth of pure blue, pure green LED, so that full-color LED display with its wide color gamut, high brightness sought after by the industry. However, due to the large deviation between the coordinates of the color coordinates of the red, green, and blue LEDs and the chromaticity coordinates of the PAL system (see Table 1), the color reproduction of the full-color LED screen is poor. Especially in the expression of human skin color, there is a clear visual deviation. As a result, color reproduction processing technology came into being. Here I recommend two color reproduction methods:
1, the red-green-blue three-color LED color coordinate space transformation, so that LED and PAL TV between the two color coordinates as close as possible, thereby greatly improving the LED display color reproduction. However, this method significantly reduces the color gamut of the LED display screen, and greatly reduces the color saturation of the screen.
2. : Correctly correct only the color gamut that is most sensitive to the human eye, and reduce the original color saturation as little as possible to other human eyes. In this way, the balance between color reproduction and color saturation can be achieved.
Third, the choice of base color wavelength:
LED display has a very wide range of applications in all walks of life, but in different application places have different requirements for the wavelength of the primary colors of the LED, some of the choice of the wavelength of the LED base color is to obtain good visual effects, some are in order to meet people's Habits, and some more are the provisions of industry standards, national standards and even international standards.
For example, the selection of the wavelength of the green tube primary color in a full-color LED display screen; in the early days, we generally used a 570-nm yellow-green LED. Although the cost is lower, the display panel has a smaller color gamut, poor color reproduction, and low brightness. After choosing a pure green tube with a wavelength of 525 nm, the color gamut of the display screen has nearly doubled, and the color reproduction degree has been greatly improved, which has greatly improved the visual effect of the display screen. For another example, in the securities market display, people are usually used to indicating that the stock price is rising in red, the stock price is falling in green, and the flat plate is expressed in yellow. In the transportation industry, the national standard strictly stipulates that the blue-green band indicates the passage of traffic and the red band is prohibited. Therefore, the choice of the wavelength of the primary color is one of the important links in the LED display.
Fourth, color uniformity treatment:
The problem of uniformity in the color uniformity of the LED display has been a problem that has plagued people in the industry for a long time. It is generally believed that the brightness of the LED can be corrected in a single point to improve the brightness uniformity. However, color unevenness cannot be corrected and can only be improved by subdividing and screening the color coordinates of the LED.
With the increasing demand for LED display screens, only subdividing and screening LED color coordinates can no longer satisfy people's critical eye. Comprehensive correction processing is applied to the display screen to improve the uniformity of color. of.
We have found that even the LED of the same brand in the international first brand has large wavelength deviations and color saturation deviations, and this deviation range greatly exceeds the human eye's discrimination threshold for green color difference. Therefore, it is important to perform color uniformity correction. meaningful.
In the CIE1931 chromaticity diagram, according to the law of the center of gravity, we found that: at any point in the G range (□abcd), the green color mixes a certain proportion of red and blue, and the color coordinates of the mixed color can be adjusted to the straight line cR. The intersection with the straight line dB.
Although the chroma uniformity can be greatly improved. However, the corrected color saturation is significantly reduced. At the same time, another premise of using red and blue to correct the uniformity of green chroma is that the red, green and blue LEDs in the same pixel are concentrated as much as possible so that the red, green, and blue color mixing distances are as close as possible to achieve better results. Effect. At present, the industry usually adopts the LED uniform distribution method to bring confusion to the uniformity of chroma. In addition, how to measure tens of thousands of red, green, and blue LED color coordinates is an extremely difficult problem. We gave a hint about this.
Fifth, the deployment of white field color coordinates:
White field color coordinate deployment is one of the most basic technologies for full-color LED displays. However, in the mid-1990s, due to the lack of industry standards and basic testing methods, the color coordinates of the white field were usually determined by human eyes and feelings, thus causing serious color casts and randomness of the white field color temperature. With the promulgation of industry standards and the completeness of testing methods, many manufacturers have begun to standardize the full color screen color matching process. However, due to the lack of theoretical guidance for color matching, some manufacturers often allocate hundreds of color coordinates at the expense of the gray levels of certain primary colors, and the overall performance cannot be improved.
In summary, we mainly discussed three aspects:
1, how to improve the LED display color uniformity;
2, how to expand the color gamut and restore more natural colors;
3, how to improve the LED display color reproduction;
The above-mentioned chroma processing technologies are all related to each other during specific implementation. In some aspects, even fish and bear's paws cannot be combined. The integrated LED display also needs to perform brightness uniformity correction, grayscale nonlinear conversion, noise reduction processing, image enhancement processing, dynamic pixel processing, etc. The entire signal processing flow is very complicated. Therefore, we must comprehensively balance various performances from the system's point of view, grasp the order of various treatments, and increase the depth of signal processing in order to enable LED full-color displays to present a colorful, colorful and exciting world.
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