contrast threshold

例句：

1. 1. The contrast threshold between the two colors is very high.
   这两种颜色的对比阈值非常高。
2. 2.The contrast threshold of the image is too low to be visible.
   图像的对比阈值太低，无法看到。
3. 3. The contrast threshold of the human eye is about 0.001 lux.
   人类眼睛的对比阈值大约是0.001勒克斯。