You can view slices in Photoshop and the Save For Web & Devices dialog box. The following characteristics can help you identify and differentiate between slices:
In addition, the Save For Web & Devices dialog box uses color adjustments to dim unselected slices. These adjustments are for display purposes only and do not affect the color of the final image. By default, the color adjustment for auto slices is twice the amount of that for user slices.
Select the Slice Select tool, and click Show Auto Slices or Hide Auto Slices in the options bar.
Choose View > Show > Slices. Auto slices appear with the rest of your slices.
In Windows, choose Edit > Preferences > Guides, Grid, Slices & Count.
In Mac OS, choose Photoshop > Preferences > Guides, Grid, Slices & Count.