Use the Edit > Inverse Select command or the [Ctrl + Shift + I] keyboard shortcut, when one or several image segments have already been selected in the active image. With this command, the image segment that have, at that moment, not been selected, will be selected.
1.To select one or more image segments, click the Marquee Tool 
button in the Toolbox toolbar.
In the left image, e.g., the blue rectangular image segment is selected.
2.Use the Edit > Inverse Select command afterwards.
The image segment that is selected now is shown in the right image.
Drawing objects
The command is not available for drawing objects.
2820 24092012