By using the Undo/Redo commands and the History panel, you can easily control the state(s) of your images.
Use the Undo or Redo commands
The Undo and Redo commands let you undo or redo operations. You can also use the History panel to undo or redo operations.
Revert to the last saved version
Restore part of an image to its previously saved version
Use the History Brush tool to paint with the selected state or snapshot on the History panel.
Use the Eraser tool with the Erase To History option selected.
Select the area you want to restore, and choose Edit > Fill. For Use, choose History, and click OK.
To restore the image with a snapshot of the initial state of the document, choose History Options from the Panel menu and make sure that the Automatically Create First Snapshot option is selected.
Cancel an operation
Receive notification when an operation is completed
A progress bar indicates that an operation is being performed. You can interrupt the operation or have the program notify you when it has finished the operation.
Using the History panel
You can use the History panel to jump to any recent state of the image created during the current working session. Each time you apply a change to an image, the new state of that image is added to the panel.
For example, if you select, paint, and rotate part of an image, each of those states is listed separately in the panel. When you select one of the states, the image reverts to how it looked when that change was first applied. You can then work from that state.
You can also use the History panel to delete image states and, in Photoshop, to create a document from a state or snapshot.
To display the History panel, choose Window > History, or click the History panel tab.
A. Sets the source for the history brush B. Thumbnail of a snapshot C. History state D. History state slider
Program-wide changes, such as changes to panels, color settings, actions, and preferences, are not reflected in the History panel, because they are not changes to a particular image.
By default, the History panel lists the previous 20 states. You can change the number of remembered states by setting a preference under Preferences > Performance. Older states are automatically deleted to free more memory for Photoshop. To keep a particular state throughout your work session, make a snapshot of the state (see Make a snapshot of an image).
Once you close and reopen the document, all states and snapshots from the last working session are cleared from the panel.
By default, a snapshot of the initial state of the document is displayed at the top of the panel.
States are added to the bottom of the list. That is, the oldest state is at the top of the list, the most recent one at the bottom.
Each state is listed with the name of the tool or command used to change the image.
By default, when you select a state, the states below it are dimmed. This way you can easily see which changes will be discarded if you continue working from the selected state.
By default, selecting a state and then changing the image eliminates all states that come after it.
If you select a state and then change the image, eliminating the states that came after, you can use the Undo command to undo the last change and restore the eliminated states.
By default, deleting a state deletes that state and those that came after it. If you choose the Allow Non-Linear History option, deleting a state deletes only that state.
Click the name of the state, and choose Delete from the History panel menu to delete that change and those that came after it.
Drag the state to the Delete icon to delete that change and those that came after it.
Choose Clear History from the panel menu to delete the list of states from the History panel, without changing the image. This option doesn’t reduce the amount of memory used by Photoshop.
Hold down Alt (Windows) or Option (Mac OS), and choose Clear History from the panel menu to purge the list of states without changing the image. If you get a message that Photoshop is low on memory, purging states is useful, because the command deletes the states from the Undo buffer and frees up memory. You can’t undo the Clear History command.
Choose Edit > Purge > Histories to purge the list of states for all open documents. You can’t undo this action.
Drag a state or snapshot onto the Create A New Document From Current State button in the History panel. The history list for the newly created document contains only the Duplicate State entry.
Select a state or snapshot, and click the Create A New Document From Current State button . The history list for the newly created document contains only the Duplicate State entry.
Select a state or snapshot, and choose New Document from the History panel menu. The history list for the newly created document contains only the Duplicate State entry.
Drag a state onto an existing document.
To save one or more snapshots or image states for use in a later editing session, create a new file for each state you save, and save each in a separate file. When you reopen your original file, plan to open the other saved files also. You can drag each file’s initial snapshot to the original image to access the snapshots again from the original image’s History panel.
You can specify the maximum number of items to include in the History panel and set other options to customize the panel.
Automatically Create First Snapshot
Automatically creates a snapshot of the initial state of the image when the document is opened.
Allow Non-Linear History
Makes changes to a selected state without deleting the states that come after. Normally, when you select a state and change the image, all states that come after the selected one are deleted. In this way, the History panel can display a list of the editing steps in the order that they were made. By recording states in a nonlinear way, you can select a state, make a change to the image, and delete just that state. The change is appended at the end of the list.
Show New Snapshot Dialog By Default
Forces Photoshop to prompt you for snapshot names even when you use the buttons on the panel.
You may need to keep careful track of what’s been done to a file in Photoshop, either for your own records, client records, or legal purposes. The Edit History Log helps you keep a textual history of changes made to an image. You can view the Edit History Log metadata using Adobe Bridge or the File Info dialog box.
You can choose to export the text to an external log file, or you can store the information in the metadata of edited files. Storing many editing operations as file metadata increases file size; such files may take longer than usual to open and save.
If you need to prove that the log file hasn’t been tampered with, keep the edit log in the file’s metadata, and then use Adobe Acrobat to digitally sign the log file.
By default, history log data about each session is saved as metadata embedded in the image file. You can specify where the history log data is saved and the level of detail contained in the history log.
Exports the history log to a text file. You are prompted to name the text file and choose a location in which to store it.
If you want to save the text file in a different location or save another text file, click the Choose button, specify where to save the text file, name the file if necessary, and click Save.
Keeps a record of each time you start or quit Photoshop and each time you open and close files (each image’s filename is included). Does not include any information about edits made to the file.
Make a snapshot of an image
The Snapshot command lets you make a temporary copy (or snapshot) of any state of the image. The new snapshot is added to the list of snapshots at the top of the History panel. Selecting a snapshot lets you work from that version of the image.
Snapshots are similar to the states listed in the History panel, but they offer additional advantages:
You can name a snapshot to make it easy to identify.
Snapshots can be stored for an entire work session.
You can compare effects easily. For example, you can take a snapshot before and after applying a filter. Then select the first snapshot, and try the same filter with different settings. Switch between the snapshots to find the settings you like best.
With snapshots, you can recover your work easily. When you experiment with a complex technique or apply an action, take a snapshot first. If you’re not satisfied with the results, you can select the snapshot to undo all the steps.
Snapshots are not saved with the image—closing an image deletes its snapshots. Also, unless you select the Allow Non-Linear History option, selecting a snapshot and changing the image deletes all of the states currently listed in the History panel.
To automatically create a snapshot, click the Create New Snapshot button on the History panel, or if Automatically Create New Snapshot When Saving is selected in the history options, choose New Snapshot from the History panel menu.
To set options when creating a snapshot, choose New Snapshot from the History panel menu, or Alt-click (Windows) or Option-click (Mac OS) the Create New Snapshot button.
To select a snapshot, click the name of the snapshot or drag the slider at the left of the snapshot up or down to a different snapshot.
To rename a snapshot, double-click the snapshot and enter a name.
To delete a snapshot, select the snapshot and either choose Delete from the panel menu, click the Delete icon , or drag the snapshot to the Delete icon.
Paint with a state or snapshot of an image
The History Brush tool lets you paint a copy of one image state or snapshot into the current image window. This tool makes a copy, or sample, of the image and then paints with it.
For example, you might make a snapshot of a change you made with a painting tool or filter (with the Full Document option selected when you create the snapshot). After undoing the change to the image, you could use the History Brush tool to apply the change selectively to areas of the image. Unless you select a merged snapshot, the History Brush tool paints from a layer in the selected state to the same layer in another state.
The History Brush tool copies from one state or snapshot to another, but only at the same location. In Photoshop, you can also paint with the Art History Brush tool to create special effects.