The Screen Capture action captures a specified object or area of the screen to the system clipboard or a named clipboard.

Select the object or area to capture from the Capture pop-up:

• all screens
• main screen
• screen with index
• the front window
• window with title
• window with title containing
• window with title matching
• window with index
• area

Select which clipboard to write to from the to pop-up.

Two options for the action are available from the gear icon in the top right corner of the action:

• Include Shadows
• Always Nominal Resolution

Nominal resolution means the images will be captured at 72dpi despite a possibly higher dpi used by the monitor (for example, if you have a retina monitor, without this option the screen capture would be at 144dpi).

Keyboard Maestro does NOT replicate OSX's interactive capture area functionality – e.g. ⌘⇧4.

Unfortunately Apple has not provided an API for that.

Therefore to use it in a script you need to use an Execute a Shell Script action:

screencapture -ic

This will capture interactively to the clipboard.

Enter “man screencapture” in the Terminal.app for more information.