Here’s a quick tip for increasing the size of the thumbnails in a SharePoint 2010 Slide Library.
When viewing AllItems.aspx, do the following:
1. Go to the Ribbon and click Library under Library Tools.
2. Click Modify View.
3. Deselect the Thumbnail column (position 2).
4. Scroll down and select the OTHER column cleverly named Thumbnail and set it to Position 2.
5. Click OK.
This will display your thumbnails in a resolution of 256 x 192 pixels instead of the default resolution of 83 x 63 pixels. Admittedly, this is not the best solution available, but it would be hard to beat the price.