A selected area is useful for applying editing locally. In default, a processing will affect a whole image. When a selected area is specified, only the selected part will be changed during the processing.
You can use selecting tools to make a selection. In the program, the most common selecting tool is 'Polygon selection tool' which operates as follows:
- Click to start. Click around the object to define the shape. Move back to the start point and click to close selection.
- Double click can end selection too.
- Right click can undo the last point.
- If a selection already exists, press ‘Shift’ to start clicking means ‘add selection to the existed’.
- Pressing ‘Ctrl’ in start means subtract.
- Pressing and moving with Right button of the mouse can switch the tool to 'Free Selection' tool.
When a selection is ready, you can see and use the small toolbar aside for modifications. It includes functions like 'feather', 'expanding', etc. You can click the 'Store current selection to area mask' button on the 'Area' table to save it to an item in the list. The areas in the list can be selected and switched to in all 'Filter dialog' (Refer to 'Filter dialog' in 'User interface' chapter and the workflow).