OFweek smart home network news In our lives, color can be said to be the most arousing people's emotional fluctuations, people will see different colors because of emotional fluctuations. However, in addition to the colors we see in everyday life, most of the rest of the time is getting color information on the TV. TVs have always played an extremely important role in the long history of human history. From the earliest black and white TVs to TVs, the TV industry that was affected by color has also undergone a fundamental change, and the entire screen output has also become live. .
High color gamut is just a gimmick?
However, with the continuous upgrading of display technology, television is not satisfied with simply presenting colors, but is more pursuing the accuracy of colors and the richness of the colors presented. Since the end of 2014, high-gamut TVs have been blessed with new backlight technology assisted by quantum dot materials, which has achieved a higher standard of color gamut coverage for televisions. So in recent years, high-color television has become the focus of TV manufacturers to promote, even with high color gamut as a gimmick to increase TV prices, to attract consumers to buy. So expensive, blind pursuit of high color television, can really bring us more amazing visual experience?
Color can make people's emotions fluctuate
The general consumer's understanding of the color gamut is that the higher the color gamut, the better the color rendering. In fact, this understanding is more one-sided. The color gamut refers to a range region formed by the number of colors that the display device can express, that is, a range of colors that can be represented by various screen display devices, printers, or printing devices. The color of the visible spectrum in the natural world constitutes the largest color space, but for so many colors it requires a more intuitive representation. The CIE International Lighting Association developed a CIE-xy chromaticity diagram for the intuitive performance gamut.
CIE chromaticity diagram (intermediate triangles are NTSC gamut)
In the CIE-xy chromaticity diagram, the range of color gamuts that can be represented by various real-world devices can be represented by a triangular region consisting of RGB three-point lines. The larger the area of ​​the triangle, the larger the gamut of the display device. . However, this range is too large for display technology. The colors we display through the screen are much smaller than this. So in 1953, the National Television Standards Institute (NTSC) developed the NTSC color gamut standard based on the CIE chromaticity diagram, and planned a 100% gamut space, quantifying the size of the gamut by percentage.
The emergence of quantum dot technology has further improved the color gamut coverage of television
The coverage of the color gamut of early LCD TVs can only reach 40% to 50% of the NTSC standard. After that, the coverage of TV color gamuts continues to increase. At present, even the most mainstream LCD TVs can reach about 72% NTSC coverage. In recent years, with the continuous development of wide color gamut technology and quantum dot technology, the NTSC gamut coverage of television has basically reached more than 90%, and some may even reach about 140%. However, such a high color gamut coverage is really as good as the manufacturers advertised?
How does the color gamut improve? Currently, there are two types of TVs on the market, namely, our common LCDs and OLEDs. The QD TV is essentially LCD because it does not get rid of the backlight control. The OLED's display principle is self-luminous. After being excited by electricity, it can directly display very pure red, green and blue primary colors, so the color gamut coverage can easily achieve a higher level. At present, OLED TVs have basically added white pixels (WRGB) to reduce the high color purity of RGB OLEDs.
At present, large-size OLEDs have added white pixels
The most effective way to enhance the color gamut is to start with the backlight and improve the purity of the backlight, especially the red, green and blue wavelengths. At present, the most mainstream method for liquid crystals is to replace the types of LED phosphors. The latest inorganic phosphors enable the white light emitted by LEDs to have higher purity in the red, green, and blue color bands, and can be greatly improved in brightness. With high-gamut TVs using a new generation of inorganic phosphors, NTSC color gamut values ​​can generally reach over 90%, and color purity and energy efficiency are significantly improved.
LCD TVs increase phosphor purity by adding phosphors
Quantum dots are the most ideal materials for improving the color gamut. Its luminescent purity is higher than that of organic molecules and is higher than that of inorganic phosphors. The stability of quantum dots is similar to that of inorganic phosphors, but the processing performance is the same as that of organic molecules. Therefore, quantum dots are quantum. The point can be said to take into account the advantages of organic and inorganic materials. Quantum-dot TVs excite quantum dot crystals on thin films by radiating pure blue light to release pure red light and pure green light, and project the remaining pure blue light onto the imaging system. This provides extremely pure light. Super LED phosphor lighting principle.
Quantum dots are currently ideal light emitting materials
In addition to starting with the purity of the backlight, raising the color gamut of the TV can also be accomplished by increasing the number of primary colors. That is, the structure of the filter plate on the liquid crystal panel is changed from the original three colors to four colors, five colors, or even more. By increasing the number of primary colors and increasing the combination of colors, more colors are displayed. However, this technology has to be greatly changed on the panel and the color grading system, and the technical difficulty and cost are high, so it has not been widely used.
3 Do not be blinded by high-color television The binocular high-gamut television can actually be called wide-gamut television. It defines the scope of the color gamut of mainstream flat-panel TVs, but there is no strict definition of the standard. However, as far as TVs are concerned, the color gamut coverage is more than 90% of NTSC and it can be called high-gamut television. In fact, the appearance of high color gamut means that TV can display more abundant colors, and the vividness of the picture has also been significantly improved. Due to the increase of color types, the color transition in the picture becomes more natural, effectively avoiding the appearance of distortion and color blocks. More kinds of colors make the screen more distinct and reveal more details and closer to the real effect.
High-gloss television makes the transition to natural colors more natural
At the same time, the colors of red, green, and blue in the high-color television display will be more pure, brighter, and closer to the true color of nature. In fact, from the CIE chromaticity diagram we can see that the red, green, and blue reference colors are all located at the periphery of the gamut space, so only the gamut range is large enough to contain more pure colors. Ordinary TV can't do the most real restoration for pure color, but high color television can show more pure.
The red, green, and blue reference colors are distributed around the gamut space
Although high-gamut TVs have many advantages, they also bring more problems. With the increase in the number of colors, although the screen is more beautiful, the colors displayed are not always accurate. High-gamut televisions have increased the variety of colors and brought a greater burden on the control of color. If the color control is not accurate enough, the displayed image will still be distorted, and it will be far from the true color. Raising the color gamut is of course a good thing, but it should take into account the control of color so that rich colors can have a real effect.
The prerequisite for improving the color gamut is to have precise control over colors, otherwise it would be counter-productive.
From the TV products tested by the author, the higher color gamut coverage does not mean that the color performance ability is stronger. In the actual measurement process, many NTSC gamut values ​​for TVs have reached more than 100%, or even more than 110%. However, through static and dynamic test observations, the color accuracy of some products did not meet expectations, and even The appearance of color cast or too bright looks very unnatural.
This is why the current color gamut coverage of mobile phone screens has shown a downward trend as a whole, because it is difficult to achieve precise control over too rich colors, and the object will be reversed. Therefore, high-gamut television also depends on the manufacturer's ability to adjust color, and can not only look at the color gamut coverage to judge its color performance. In the actual testing process, the color gamut coverage of the top TV products under the joint venture brand is basically maintained at between 85% and 95%, and color tuning is very accurate. If you are a user who has an utmost pursuit of color, the high-end products under the joint venture brand are still very trustworthy. At the same time, the domestic brand Hisense has also done very precise (measured) in color tuning.
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