Microsoft Expression Media enables you to view each item in your catalog by opening the original file and dynamically displaying it in Media view, Slide Shows, and Light Table mode.
In Expression Media, you also have the option of creating media previews: large proxy images in a .jpg file format that Expression Media displays in Media view, Slide Shows, and Light Table mode.
Media Previews are especially useful if most of your media is stored on offline storage volumes, such as a CD or DVD. These previews are also useful for distributing catalogs without having to include the original media files.
To create a catalog with Media Previews
Create a new catalog.
On the Edit menu, click Thumbnails and Previews.
Select the Create full-screen previews check box. This enables the creation of Media Previews.
Select the size of previews to be created (for example, 800, 1024, or 1280 pixels).
Select the .jpg compression quality to be applied to the preview images, and then click OK.
Import the media items.
The file size of catalogs with Media Previews can be much larger than that of catalogs with only thumbnails. The size and compression quality of media previews also greatly affects the file size of Expression Media catalogs. Because Expression Media has to render the complete image in order to create a full-screen preview, using Media Previews can slow down the import process.
The time it takes to organize media varies based on your computer's operating system and overall speed. It also varies depending on the size of the original media files.