Power View in SharePoint saves an image of each view in its current state as a preview for other users (in Power Pivot Gallery, PowerPoint, and other applications). View preview images are the images that Power View displays in the View pane in design mode. They are snapshots of a view. When you save a Power View report, by default these images are saved with the report. They are then displayed:
In the Power Pivot Gallery in SharePoint Server 2013, just as Microsoft Excel worksheets are displayed.
In PowerPoint design mode, as the static images of the views when you export your report.
However, the first time you save a file, or when you save as, you have the option not to save them.
Turn off saving preview images with a report
On the Power View File menu, click Save As.
In the Save As dialog box, clear the Save preview images with report check box.
Caution: Consider not saving preview images if they display information that you consider potentially sensitive. Keep in mind that in the Power Pivot Gallery Carousel view displays images that are large enough to be readable. Views without preview images are shown with a watermark icon and a label, 'Preview not available'.
Also, if you open and view the views in a report that has saved preview images, when you save the report you are saving the updated preview images. To avoid this, click Save As instead.
Carousel view in the Power Pivot Gallery in SharePoint
There are two versions of Power View: Power View in Excel 2013 and Power View in SharePoint 2013. This topic is only about Power View in SharePoint 2013.If you save an Excel workbook containing Power View sheets to a SharePoint library with Excel Services, you see the Power View sheets along with the other sheets in the workbook.
Read about everything else you can do in Power View.