Laura Balsam
Classes Outlines

Most Picasa users have their photos saved in the JPG file format.

JPG's are compressed files. Each time you re-save a JPG file, the image is re-compressed. Image detail is lost and JPG "artifacts", or noise, is introduced.

In order to protect your photos Picasa does not re-save the image file each time you make a change to it. Instead, it accumulates the changes and makes them all at once, minimizing the effects of JPG re-compression.

Each time you make a change, the library view in Picasa reflects that change, but the JPG file on the hard drive is not modified.

If one or more files in a folder has been changed in Picasa a Save to DIsk button will appear in the upper right area of the library.

You will also see how many changes have been made to files in this folder.

When you click the Save to DIsk button, Picasa makes the changes that have been stored, re-compresses and re-saves the file(s).

Until this has been done, only Picasa knows about the changes. Other programs, including Windows, will see the photo without the changes you made in Picasa.