It is the ratio of the black and white of the screen, that is, the gradient from black to white. The larger the ratio, the more gradient levels from black to white, and the richer the color performance. In the projector industry, there are two kinds of contrast test methods, one is a full-on/full-off contrast test method, that is, the ratio of the full white screen to the full black screen luminance of the test projector output. The other is ANSI contrast, which uses the ANSI standard test method to measure contrast. The ANSI contrast test method uses 16-point black and white color blocks. The ratio between the average value of the eight white areas and the average value of the eight black areas is ANSI. Contrast. The difference in contrast values ​​obtained by these two measurement methods is very large, which is also an important reason why different manufacturers' products have large differences in the nominal contrast.

The effect of contrast on visual effects is critical. In general, the greater the contrast, the clearer and more eye-catching the image, the brighter the colors, and the less contrast, the more gray the entire screen will be. High contrast is very helpful for image clarity, detail performance, and grayscale performance. In some black and white contrast text display, CAD display and black and white photo display, etc., high contrast products in black and white contrast, clarity, integrity and other aspects have advantages. In contrast, high contrast has no obvious effect on the image in terms of color gradation. Contrast has more influence on the dynamic video display effect. Because the light and shade conversion in the dynamic image is faster, the higher the contrast, the easier the human eye can distinguish the conversion process. High-contrast products have more obvious advantages in details, sharpness, and high-speed moving objects in some dark scenes.

In the aspect of contrast adjustment, there are also great differences in the processing methods of various products. The contrast adjustment range of some products is very small, and the adjustment process is more biased toward changing the image brightness (increasing the brightness of highlight areas). The contrast of some products is very large, and the contrast of different adjustment values ​​for the image is relatively large, so that the user can adjust the contrast according to different display contents to achieve the best display effect. There are also some products with little difference in contrast adjustment and brightness adjustment. Contrast adjustment can assist in brightness adjustment. The realization of contrast is also closely related to the imaging device and the optical path design of the projector. For LCD projectors, the first factor is the pixel transmittance and blocking rate of the LCD panel. The greater the difference, the better the contrast of the projector. The bigger.

The nominal contrast ratio of most current LCD projectors is around 400:1 (ANSI), and the nominal contrast of most DLP projectors is above 1500:1 (full white/all black). The higher the contrast, the higher the price of the projector. If you only use the projector to display text and black and white pictures, the projector with a contrast ratio of about 400:1 can meet the needs. If you use it to demonstrate colorful photos and play video animations, it is best. Choose a high-profile projector that is over 1000:1.