October 30, 2012, 3:52 PM — Here's how you can see a larger preview of a file in the Get Info menu in OS X Mountain Lion.
1. Select the file.
2. Press Command + I on your keyboard (or select File then Get info from the file's menu in the menubar).
3. Go to the Preview tab.
4. You'll see a small preview of the file.
5. Double click the preview.
6. A larger preview will pop up on your screen.
For more, see the original article at the link below.
Use the Get Info window in Mac OS X | Daily Mac Tips