Simply put, contrast refers to the measurement of different brightness levels between the brightest white and the darkest black in an image. The larger the difference range, the higher the contrast, the smaller the difference range and the smaller the contrast value. At present, the static comparative value is usually calculated by dividing the white brightness by the black brightness, so the brighter the white, the darker the black, and the higher the contrast. Visually speaking, the higher the contrast, the brighter the color of the picture and the brighter the whole picture. Moreover, the contrast is small, which will cast a layer of "fog" on the whole picture and look gray. High contrast is very helpful for image clarity, detail expression and gray scale expression. High-contrast products have advantages in text display, black-and-white photo display, black-and-white contrast, clarity and integrity.

Relatively speaking, at the color level, the influence of high contrast on the image is not obvious. In fact, in daily use, contrast has a greater impact on the display effect of dynamic video. Because the transition between light and dark in dynamic pictures is very fast, the higher the contrast, the easier it is for human eyes to distinguish the transition process. The dynamic contrast ratio as high as hundreds of thousands and millions to one is generally that manufacturers deliberately guide consumers to carry out publicity, so that consumers mistakenly think that such TV products have high specifications and good picture performance. Dynamic contrast and actual contrast are completely two concepts. Generally, the dynamic contrast is 5- 10 times of the actual contrast, which has no practical reference significance. Therefore, when consumers buy TV, they only need to pay attention to the static contrast of TV. Dynamic contrast not only makes us feel the process of light-dark conversion more intuitively in dynamic pictures, but also is used to control the phenomenon of TV light leakage. The principle of dynamic contrast is realized by controlling the backlight current. When a bright picture is presented, the backlight current will increase, so that the whole picture will become brighter. When a dark picture is presented, the backlight current will be reduced to reduce the brightness, so as to obtain a larger contrast value and control the light leakage phenomenon of the TV. At present, the dynamic contrast function of many TV products is turned on by default, and even if it is turned off, at least half of the effect will be retained.