Undo Brush Tool

The Undo Brush Tool can be used to selectively undo modifications to individual pixels, restoring them to a previously targeted history state.

After setting a brush source, you can blend the image's current state back to a previous state, like painting backwards in time.

The following settings can be adjusted from the context toolbar:

Width—the brush (stroke) size in pixels.
Opacity—how see through the brush is.
Flow—how fast the brush effect is applied (1% is very slow, 100% is immediate).
Hardness—how hard the edges of the brush are. The brush appears softer as the percentage decreases.
More—tap to display the Brushes dialog to access advanced brush settings.
Blend Mode—changes how the applied pixels interact with existing pixels on a layer. Select from the pop-up menu.
Blend—when enabled (default), pixels which do not overlap those in the selected history state are unaffected, allowing the blending of the current document state with the selected, previous state. If this option is off, all pixels are returned to the previous state when painted.
Protect Alpha—when enabled, you are not able to paint on the current layer's transparent regions.
Symmetry—when the Lines setting is set to greater than 0, repeats the brush stroke around a number of axes (defined by the value). The centre axis point can be repositioned by dragging it.
Mirror—with symmetry enabled, causes brush strokes to be mirrored along the X and Y axis.
Lines—with symmetry enabled, defines the number of axes around which the brush stroke will be repeated.
Locked—when enabled, prevents the symmetry line from being moved.