First of all, the answer to this question is green. The Hollywood sci-fi blockbusters we watched, and the special effects shots were all done under the green screen. The background color of Gao Fancha is positive. The greater the contrast between the object and the background color, the easier it is to crop the picture.

Use the quick selection tool or magic wand tool to frame the theme image.

As shown in the figure below, the magic wand tool can be done in one go.

If you find that the picture has white edges, you can continue to execute.

Black and white mask layer, and then click Filter-Other-Minimum.