After you’ve captured an image in Photo Booth, you can save it as a separate file by following these steps:
Follow the steps in Viewing Photo Booth Pictures in Viewing Photo Booth Pictures.
Click the image you want to save as a separate file.
Select File ▸ Export (or right-click the picture in the Photo Booth window and choose Export from the pop-up menu). A Save dialog appears.
Type a descriptive name for your picture.
(Optional) Click the Where pop-up menu and choose a folder to store your picture in. If you do not select a folder, Photo Booth will store your picture in the Pictures folder.
Click Save.