The Characterics of Contrast Radio

- Nov 12, 2018-

   Contrast refers to the measurement of different brightness levels between the brightest white and the darkest black in the dark and dark areas of an image. The larger the difference range is, the larger the contrast is. The smaller the difference range is, the smaller the contrast is, the better the contrast ratio is 120. :1 makes it easy to display vivid, rich colors, and when the contrast ratio is as high as 300:1, it can support the colors of each step. However, the ratio is subject to the same dilemma as brightness. There is no effective and fair standard to measure the contrast ratio, so the best way to identify it depends on the user's eyes.


  In the darkroom, the brightness under the white screen (when it is the brightest) is divided by the brightness of the black screen (the darkest). More precisely, contrast is the subtraction of the white signal at 100% and 0% saturation, divided by the white value of 0% (in illuminance, ie lux, lumens per square meter). The 0% white signal is actually black), the value obtained. Contrast is the division of the whitest and darkest luminance units. Therefore, the brighter the white, the darker the black, the higher the contrast. Strictly speaking, the contrast we refer to is the ratio of the brightness of the brightest point (white) to the darkest (black) at the same point on the screen, but usually the contrast indicator of the product is for the entire screen, for example, a screen is all white. The brightness of the screen is 500cd/m2, and the brightness of the black screen is 0.5cd/m2, so the contrast of the screen is 1000:1.


  The effect of contrast on the visual effect is very important. Generally speaking, the contrast is larger, the image is more clear and conspicuous, and the color is more vivid and vivid; while the contrast is small, the whole picture is grayed out. High contrast is very helpful for image sharpness, detail performance, and gray level performance. In some black and white contrast text display, CAD display and black and white photo display, high-contrast products have advantages in black and white contrast, clarity, and integrity. Relatively speaking, in terms of color gradation, the effect of high contrast on the image is not obvious. Contrast has a greater impact on the dynamic video display. Because the light and dark transitions in the dynamic image are faster, the higher the contrast, the easier it is for the human eye to distinguish such a conversion process. High contrast product adjustments have two ways to increase contrast:


1. Improve the brightness of the white screen.


2. Make black blacker and lower the minimum brightness. This may be a little difficult to understand. First of all, you need to know how to control the light and dark changes of the liquid crystal display. It is impossible to open and close the light tube, but the liquid crystal cannot be done. It is 100% light-free, so even if it is adjusted to a pure black screen, the LCD will still have some brightness. This is a problem of denominator and numerator. The denominator is small and the contrast is naturally high.


  The method of increasing the brightness and increasing the contrast is relatively simple, but the brightness cannot be increased indefinitely due to problems such as lamp life, liquid crystal leakage, and the like. The second method is the development direction of many high-end LCD manufacturers, which is why liquid crystals with low brightness can achieve high contrast. When purchasing a liquid crystal display, you should pay attention to whether the display screen has color distortion due to highlighting, because such high contrast has no reference value. More importantly, the high brightness does not lead to a better display. It only makes the light image into a single image, but it does not help the dark part.

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