
You can also generate full-size previews for all files in a folder. See Show hidden files, folders, filename extensions | Windows XP, Vista, Windows 7. Note: On Windows, turn on Show Hidden Files to see this location.

When you use this cached file, you avoid rerendering a 100% image from the original source file. It is also what you see when you use the Loupe tool in Review mode or the Preview panel. This zoom-in is what you see in a slideshow and in full-screen preview.

100% Preview, also called full-size cache, is a JPEG file that displays the 100% zoom-in.
