How does the mobile phone version of Mito Xiu Xiu change the background of the characters?

Let's take Meitu Xiu Xiu app in Apple's 7s mobile phone as an example to show you.

1. First, click Meitu Xiu Xiu on the mobile phone desktop.

2. Then click on the beautification picture.

3. Then click on a person's picture.

4. Then click Filter.

5. Then click on the artistic scenery.

6. Then click on a character background you want.

7. Then click "√" in the lower right corner of the screen.

8. Finally, click Save and Share in the upper right corner of the screen. Through the above operations, the background of the figure in the picture is successfully replaced by Meitu Xiu Xiu.