What is the red background of SLR shooting and how to adjust it?

Because the background is white and there is a red object in front of it, it will be red.

Correct words:

1, late PS color matching

2. Add two more background exposures. If it is too violent, there will be no red overflow.

3. The still life is far away from the background, and black cloth is put on the edge of the still life to absorb light and prevent red from overflowing.