[watsonm]

>I had heard that it was every time you open a jpeg

This probably comes from those dubious applications that re-save in the background when you didn't really want them to.

If you ask an application to rotate a picture (since it is in portrait mode) it may save then or may save when you exit, or may save when you move on to the next picture.

Hopefully it will ask if you wish to save/overwrite but some programs may well have the option to save/overwrite automatically without asking.

You just have to be careful and should probably do so experiments to see if the modify date/timestamp has changed!

Mike