Undoing and Redoing History Palette Actions

The History palette lists all actions performed on the active image. The most recent action is at the top of the list, and the first action performed is at the bottom of the list. You can select an individual action to modify by clicking its name in the History palette, or select multiple actions by holding down Shift (to select adjacent actions) or Ctrl (to select non-adjacent actions).

After applying any number of actions to an image, you can use the History palette to:

Undo any listed action by clicking its Undo/Redo button , or by highlighting the item name and then pressing the Undo to here button on the History palette's toolbar. Both methods perform an "Undo to here" function, undoing the action you clicked as well as all subsequent actions (which are listed above the action you clicked). The undone actions will be denoted with a yellow X .
Redo an undone action by again clicking its Undo/Redo button, or by highlighting the item name and then pressing the Redo to here button on the History palette's toolbar. Both methods perform a "Redo to here" function, redoing the action you clicked as well as all preceding actions (which are listed below the action you clicked). The redone actions will no longer have an X of any color over their eye icon. Note that selectively undone actions (denoted with a red X) that precede the action you clicked will not be redone. These actions can only be redone via the Redo selected command described below.
Selectively undo an action by holding down Ctrl and clicking its Undo/Redo button, or by highlighting the item name and then pressing the Undo selected button on the History palette toolbar. Selectively undone actions will be denoted by a red X . Be aware that a selectively undone action can yield unintended or unexpected results depending on its relationship to subsequent actions. Refer to the section Using the Selective Undo Feature Carefully below for more information.
Redo a selectively undone action by highlighting the item name and then pressing the Redo selected button on the History palette toolbar, or by Ctrl-clicking it again.

Using the History Palette's Undo and Redo Toolbar Buttons

The table below lists the function of each undo/redo-related button in the History palette.

Undo to here	Click a History palette item name and then click this button to undo the item and all actions that followed it. Clicking this button is equivalent to clicking an item's eye icon.
Redo to here	Click an undone (yellow X) History palette item name and then click this button to redo the action and any other undone actions preceding it. Clicking this button is equivalent to clicking an item's yellow-X eye icon.
Undo selected	Click a History palette item name and then click this button to selectively undo the item. Be aware that this may or may not affect subsequent actions, and may not yield the intented results. Clicking this button is equivalent to holding down Ctrl and clicking an item's eye icon.
Redo selected	Click a selectively undone History palette item name and then click this button to redo the action. Clicking this button is equivalent to holding down Ctrl and clicking an item's red-X eye icon
Clear selectively undone commands	Click this button to convert all selectively undone actions into non-undoable commands (commands that can no longer be undone or redone). You'll be prompted whether or not to perform this action.
Show non-undoable commands	Click this button to show or hide the non-undoable commands. When shown, non-undoable items will be listed in gray (denoting that they're inactive/unavailable).
Empty history	Click this button to convert all History palette items into non-undoable commands. You'll be prompted whether or not to perform this action.

Using the History Palette's Context Menu

Right-click on a selected History palette item (or group of selected items) to display the context menu, which contains all History palette-related commands.

Using the Edit Menu's and Standard Toolbar's Undo/Redo Commands

You can still use the Standard toolbar's Undo and Redo buttons, press Ctrl+Z or Ctrl+Alt+Z, or choose Edit > Undo / Redo to undo or redo actions in the order they were performed. Using these methods will update the History palette Undo/Redo button to the appropriate state ( for undone items, and for redone items). Be aware, however, that selectively undoing an action can only be performed via the History palette.

Using the Selective Undo Feature Carefully

The History palette's selective undo feature is powerful and convenient, but under certain circumstances may not be the ideal course of action. Shown below are two examples showing the results of the selective undo feature.

A Simple Example

Click here to see an image containing five individual paint strokes placed left to right across the image.
Click here to see what happens when we selectively undo the second and third strokes.

An Example of Unintended Results

Click here to see a photo that could benefit from straightening as well as the Fill Flash filter applied to the foreground.
Click here to see the photo after being straightened with the Straighten tool and cropped by marking the Crop image option in the Tool Options palette.
Click here to see a Freehand selection of the foreground area.
Click here to see the Fill Flash filter (with the Strength setting of 60) applied to the selection.
Click here to see what happens when we selectively undo the straightening by clicking the Undo selected button on the History palette toolbar. Clearly this adversely affected the Freehand selection and the Fill Flash applied to it.