4.7. Scissors Tool

The Intelligent Scissors tool is a very interesting piece of equipment. It will guess the edges that you're trying to select. It's quite hard to fully control the Free-hand tool, unless you're extremely dexterous. This is where Intelligent Scissors comes in. This tool lets you draw the outline of an object, just like the Free-hand tool (you can be a bit sloppier), but when you have defined your selection, it will automatically seek out the edges of the object that you are trying to select.

Each time you left-click with the mouse, you create a new control point, which is connected to the last control point by a curve that tries to follow edges in the image. To finish, click on the first point (the cursor changes to indicate when you are in the right spot). You can adjust the curve by dragging the control points, or by clicking to create new control points. When you are ready, click anywhere inside the curve to convert it into a selection.

[Warning] Warning
Be sure not to click inside the curve until you are completely done adjusting it. Once you have converted it into a selection, undoing takes you back to zero, and you will have to to start constructing the curve again from scratch if you need to change it.

Unfortunately, there seem to be some problems with the edge-following logic for this tool, with the result that the selections it creates tend to be pretty ugly in a lot of cases. A good way to clean them up is to switch to QuickMask mode, and use paint tools to paint in the problematic parts.

Activate Tool

  • The Scissors Tool can be called in the following order, from the image-menu: Tools/ Selection Tools/Intelligent Scissors.

  • The Tool can also be called by clicking the tool icon:

Key modifiers (Defaults)

Shortcut

The i key will change the active tool to Intelligent Scissors.

Ctrl

Holding Ctrl while creating a selection will place the selection into subtraction mode (see above).

Alt

Holding Alt will allow movement of the current selection.

Shift

Holding Shift while creating a selection will change the selection mode to addition (see above).

Ctrl+Shift

Using Ctrl-Shift will change the selection mode to intersection (or union).

Options

Overview

The available tool options for Intelligent Scissors can be accessed by double clicking the Intelligent Scissors tool icon.

Mode

Replace mode will cause any existing selection to be destroyed or replaced when the new selection is created.

Add mode will cause the new selection to be added to any existing selection regions.

Subtract mode will remove the new selection area from any existing selection regions.

Intersection mode will make a new selection from the area where the existing selection region and the new selection region overlap.

Antialiasing

This option performs no function for this tool and is present to unify the user interface between the various selection types.

Feather Edges

The Radius slider adjusts the amount of feathering in pixels for the next selection that is created. For further information regarding feathering, see the glossary entry Feathering.

Show Interactive Boundary

If this option is enabled, dragging the node during placement will indicate the path that will be taken by the selection line.

Additional information

[Note] Note
Selections can exist on the visible canvas only. However, selection movements and changes are kept in the undo buffer should you need to repair an error.