Export an image from iMovie on Mac

You can export a single frame of video in your movie as an image to use with other applications. The image is saved in the JPEG format.

In the iMovie app on your Mac, skim a clip in the browser or a movie in the timeline, and click when you reach the frame you want to export.
Click the Share button in the toolbar, and then click Image.
In the dialog that appears, type a name in the Save As field, or leave the default name, which is the name of the movie, trailer, or clip.
Navigate to the location where you want to save the file, and click Save.
After the share process is complete, a “Share Successful” notification appears.

Helpful?

iMovie User Guide