Many functions which are accessible via the image menu have a default keyboard shortcut. You may want to create a new shortcut for a command that you use a lot and doesn't have one or, more rarely, edit an existing shortcut. There are two methods for doing this.
Postup 12.1. Using dynamic keyboard shortcuts
First, you have to activate this capability by checking the Use dynamic keyboard shortcuts option in the Interface item of the Preferences menu. This option is usually not checked, to prevent accidental key presses from creating an unwanted shortcut.
While you're doing that, also check the Save keyboard shortcuts on exit option so that your shortcut will be saved.
To create a keyboard shortcut, simply place the mouse pointer on a command in the menu: it will then be highlighted. Be careful that the mouse pointer doesn't move and type a sequence of three keys, keeping the keys pressed. You will see this sequence appear on the right of the command.
It is best to use the Ctrl+Alt+Key sequence for your custom shortcuts.
Postup 12.2. Using the Keyboard Shortcut Dialog
The Keyboard Shortcuts Dialog can be used to assign keyboard shortcuts. Not only for menu commands, but also for any other command and it does not need changing any preference.