Adobe Photoshop CS2

Undoing Previous Actions

If you have mistakenly deleted or added an unwanted element to an image, you can use one of Photoshop's undo features to correct the mistake. You can undo your last action using the Undo command found in the Edit menu. If you would like to undo a previous action, but the Undo command is disabled, you may use the Step Backward command or the History palette.

Using the Undo Command
Using the Step Backward Command
Using the History Palette

Using the Undo Command

You can undo your last action using the Undo command found in the Edit menu. Unlike Microsoft Word, Photoshop does not allow you to use the Undo command to correct multiple actions.
NOTE: If the Undo command is unavailable, the option either appears disabled or as a Redo command function.

From the Edit menu, select Undo
OR
Press [Ctrl] + [Z]
NOTE: The Undo menu option will read Undo Action (where Action represents the last action you completed).

Using the Step Backward Command

The Step Backward menu option allows you to sequentially undo more than one action.

From the Edit menu, select Step Backward
OR
Press [Alt] + [Ctrl] + [Z]
Repeat step 1 as needed

Using the History Palette

Every action or change in an image constitutes a new image state. By default, the History palette records and displays the 20 most recent image states. By selecting a previous image state from the History palette you can begin working from that point, erasing all states that followed it. To keep a particular state saved in the History palette throughout the whole work session, a snapshot can be made.
History palette

Accessing the History Palette

The History palette shares a window with the Actions palette and Tool Presets palette. If the History palette is closed, open it by doing the following:

From the Window menu, select History
NOTE: A checkmark will appear next to History when the History palette is displayed.
OR
If the History palette window is open, but the Actions palette or Tool Presets palette is visible, select the History tab
The History palette appears on the right side of the screen.

Undoing Actions with the History Palette

From the History palette, select the image state you would like to revert to
Begin working on the image from that state

Making a Snapshot

The Snapshot command lets you make a temporary copy (or snapshot) of any image-state. The new snapshot is added to the list of snapshots at the top of the History palette. Selecting a snapshot lets you work from that version of the image.

At the bottom of the History palette, click CREATE NEW SNAPSHOP
The new snapshot is created in the snapshot section of the History palette.
OR
Right click the state you want to make the snapshot of,
1. Select New Snapshot...
  The New Snapshot dialog box appears.
2. In the Name text box, type a name for the snapshot
3. In the From pull-down menu, make the appropriate selection
  Full Document makes a snapshot of all layers in the image at that state
  Merged Layers makes a snapshot that merges all layers in the image at that state
  Current Layer makes a snapshot of only the currently selected layer at that state