When the weather station was making the weather forecast, the host stood in front of a blue hanging cloth. How did the weather forecast look like it was broadcast on TV?

Blue cloth is good.

The reason for doing this is very simple and easy for computer processing. Make the color part of the curtain transparent and add the required background, and the main special effects will come out. It makes sense to use blue as the color of the curtain, because the main subjects are generally characters, and the most common color among people's clothes, hair, and skin color is blue, so the blue curtain should be the most widely used. People gradually use stunt backgrounds , called blue screen.

In fact, blue screen has gradually become a historical term. Not only is the color not limited to blue, but the background color requirements are also getting lower and lower. Even the main body without a curtain can be cut out for stunts. It’s not that difficult (the same applies to the background). If you look at Forrest Gump, there are old news footage, the original historical figures are extracted, and then Tom Hanks’ modern performance image is added to it, and it is done perfectly.