What is the meaning of "positive color" in Hanfu?

In the color of clothing, the Han people regard cyan, red, soap, white and yellow as "positive colors". Different dynasties also have their own opinions, generally Xia Hei, Shang Bai, Zhou Chi, Qin Hei and Han Chi. In the Tang Dynasty, yellow was worn and the flag was red. In the Ming Dynasty, red was the right color. But since the Tang Dynasty, yellow has long been regarded as a noble color, and emperors and dignitaries often wear it.