Note on photo storage and Picasa/your Computer Hard Disk

Recover Deleted Pictures From Picasa and From Computer Hard Disk: "Picasa"

"Picasa is an application that acts as a photo organizer and editor. It does not store the image files, but simply accesses them when the user wishes to either view or edit the file. To put it simply, it means that any task performed on the file in Picasa, is actually done to the original file"... (as stored on your hard drive).