© 2007 JupiterImages.com
In This Chapter
Choosing History panel options 165
Deleting and clearing history states 168
Creating documents from states 171
Using the History panel, you can selectively undo or restore previous stages (called “states”) of a work session. In this chapter, you’ll learn how to restore, delete, and clear history states; preserve states by using snapshots; create a new document from a state or snapshot; and restore areas of an image to a prior state by using the History Brush or by filling a selection or layer with a history state.
The History panel
displays a list of the most recent states (edits) made to the currently open document. The bottommost state is the most recent. Click a prior state, and the document will be restored to that stage of the editing process. What happens to the panel when you do this depends on whether it’s in linear or nonlinear mode,A so you need to learn how these two modes differ.
A The History panel shown here is in linear mode. Note that all the steps below the current state are dimmed.
To choose a mode for the panel, choose History Options from the panel menu, then in the History Options dialog, check or uncheck Allow Non-Linear History.
We recommend keeping the History panel in linear mode (unchecking the Allow Non-Linear History option).A In this mode, if you click an earlier state and resume image editing from that state or delete it, all subsequent (dimmed) states will be discarded. This gives you the option to revert back to an earlier state with a nice, clean break.
A In the History Options dialog, check whether or not to Allow Non-Linear History.
In nonlinear mode, if you click on or delete an earlier state, subsequent states won’t be deleted or become dimmed. If you resume image editing when an earlier state is selected, your next edit will show up as the latest state on the panel, and all the states in between will be preserved. That is, the latest state will incorporate the earlier stage of the image plus your newest edit. If you change your mind, you can click any in-between state whenever you like and resume editing from there.B Nonlinear is the more flexible of the two modes, but it’s also potentially more confusing and disorienting. (We offer a more complete explanation of nonlinear mode, including an example that demonstrates how to use it, in our Visual QuickPro Guide to Photoshop.)
B Because this History panel is in nonlinear mode, all the states are available, even those that are listed below the current state.
The last option in the History Options dialog, Make Layer Visibility Changes Undoable, controls whether the hiding and showing of layers via the visibility icon on the Layers panel is listed as a state on the History panel. We prefer to keep this option off.
To specify the number of states that can be listed on the panel at a time, go to Preferences (Ctrl-K/Cmd-K) > Performance and enter a History States value (1–1000; default 20). If the maximum number of history states is exceeded during an editing session, earlier steps will be removed automatically to make room for the new ones. The maximum number of states may be limited by various factors, including the image size, the kind of edits that are made to the image, and currently available memory. Each open document has its own list of states. Note! Regardless of the preference setting, when you close a document, all the history states are deleted!
To summarize, if the History panel is in linear mode (the Allow Non-Linear History option is off) and you click an earlier state, all the states below the one you click will become dimmed. If you then delete the state you clicked or continue editing the image with that earlier state still selected, all the dimmed states will be deleted. (If you change your mind, you can choose Undo immediately to restore the deleted states.) If the panel is in nonlinear mode and you click an earlier state, then perform another edit, the new edit will become the latest state, but the prior states won’t be deleted.
To change history states:
- Perform some edits on an image.
- Do one of the following:
Click a state on the History panel.
AA This is after we clicked a prior state, with the History panel in linear mode.
On the left side of the panel, drag the History State slider
upward or downward to the desired state.To Step Forward one state, press Ctrl-Shift-Z/ Cmd-Shift-Z; or to Step Backward one state, press Ctrl-Alt-Z/Cmd-Option-Z.
• When you choose File > Revert, it becomes a state on the History panel, and like other states, all the states preceding it are preserved. You can restore the image to a state prior to the Revert one.
If you followed our advice and your History panel is in linear mode (the Allow Non-Linear History option is unchecked) and you delete a state, that state and all subsequent ones will be deleted.
Do one of the following:
Right-click/Control-click a state on the History panel and choose Delete from the context menu,A then click Yes when the alert dialog appears.B
A Right-click/Control-click a state and choose Delete from the context menu, then click Yes in the alert dialog.
B Because our History panel was in linear mode (Allow Non-Linear History unchecked) when we deleted the “Lasso” state (see the previous figure), all the subsequent states were deleted in addition to that one.
To bypass the alert, drag the state to be deleted over the Delete Current State button
on the History panel.
To delete previous states sequentially, click a state, then Alt-click/Option-click the Delete Current State button as many times as needed. (Note: The Undo command will restore only the last state you deleted.)
To clear all the states (but not the snapshots) from the History panel for all currently open documents in order to free up memory, choose Edit > Purge > Histories, then click OK. This command can’t be undone!
To clear all states (not snapshots) from the History panel for just the current document, Right-click/Control-click any state and choose Clear History. This command can be undone.
A snapshot is like a copy of a history state, with one major difference: Unlike a state, a snapshot remains on the panel even if the state from which it was created is deleted because the maximum number of history states was reached or the panel was cleared or purged. Like history states, however, all snapshots are deleted when you close your document.
In these instructions, you’ll choose snapshot options, which affect all Photoshop files; on the next page, you’ll learn how to create snapshots for a particular file.
To choose snapshot options:
- Choose History Options from the History panel menu. The History Options dialog opens.A
A There are three snapshot options in the History Options dialog.
- Check or uncheck any of the following options:
Automatically Create First Snapshot to have Photoshop create a snapshot every time you open a file (this option is checked by default).
Automatically Create New Snapshot When Saving to have Photoshop create a snapshot every time you save a file. The time of day that the snapshot was created will be listed next to the snapshot thumbnail.
Show New Snapshot Dialog by Default to have the New Snapshot dialog appear whenever you click the New Snapshot button, allowing you to choose options.
- Click OK.
If the Automatically Create New Snapshot When Saving option is off, you should get in the habit of creating snapshots periodically as you work and before running any actions on your document. If you use the New Snapshot dialog (the second method below), you’ll be able to choose whether the snapshot is made from the full document, from merged layers, or from just the current layer.
To create a snapshot of a state:
Method 1 (without choosing options)
- Edit your document so it contains the changes that you want to capture as a snapshot.
- If the Show New Snapshot Dialog by Default option is off in the History Options dialog, click the New Snapshot button.
If this option is on, Alt-click/Option-click the New Snapshot button. A new snapshot thumbnail will appear after the last snapshot in the upper section of the panel.
Method 2 (choosing options)
- To create a snapshot of a layer, click that layer on the Layers panel.
- Right-click/Control-click a history state and choose New Snapshot.A The New Snapshot dialog opens.B
A Right-click/Control-click a state and choose New Snapshot from the context menu.
B In the New Snapshot dialog, enter a name and choose which part of the image you want the snapshot to be created from.
- Type a Name for the snapshot.
- Choose an option from the From menu:
Full Document to create a snapshot from all the layers on the Layers palette. This is useful if you want to preserve all the edits at a particular stage of your document.
Merged Layers to merge all the layers on the Layers panel at that state into the snapshot.
Current Layer to make a snapshot from only the currently selected layer in its current editing state.
- Click OK.C
C A thumbnail for the new snapshot appears on the History panel.
• If the Show New Snapshot Dialog by Default option is on in the History Options dialog, you can also open the New Snapshot dialog by clicking a state, then clicking the New Snapshot button
at the bottom of the panel. Or if the dialog option is off, Alt-click/Option-click the New Snapshot button to open the dialog.
To make a snapshot become the current state:
Do either of the following:
Click a snapshot thumbnail. If the History panel is in linear mode (as we recommend), the document will revert to the snapshot stage of editing, and all the states will be dimmed. If you now resume editing, all the dimmed states will be deleted.
Alt-click/Option-click a snapshot thumbnail to have earlier states remain available and to have that snapshot become the latest state. This is a useful option if you want to preserve earlier edits.
Do either of the following:
Click the snapshot, right-click/Control-click and choose Delete (or click the Delete Current State button), then click Yes.
To bypass the prompt, click the snapshot, then Alt-click/Option-click the Delete Current State button.
By using the New Document command, you can spin off versions of your current document based on any state or snapshot.
To create a new document from a history state or snapshot:
Do either of the following:
Right-click/Control-click a snapshot or a state, then choose New Document from the context menu.A
A Right-click/Control-click a snapshot or state and choose New Document.
Click a snapshot or a state, then click the New Document from Current State button.
A new document window will appear onscreen, bearing the title of the snapshot or state from which it was created, and “Duplicate State” will be the name of the starting state for the new document.B Be sure to save this new document.
B This is the History panel for the new document.
When you draw strokes on a document with the History Brush tool, pixels below the pointer are restored from whichever state or snapshot you have designated as the history source.
Note: The History Brush tool can’t be used if certain kinds of edits were made after the document was opened, such as cropping, changing the document color mode or canvas size, or adding or deleting layers. Furthermore, the tool can’t restore deleted or modified layer effects, vector data (type or shapes), pixels from a deleted layer, or the effects of an adjustment layer. Moral: Keep your layers!
To use the History Brush tool:
- Open an image, and make some edits. (For the image shown at right, we duplicated an image layer via Ctrl-J/Cmd-J, renamed the duplicate, and applied a filter to it.) A–C
A This is the original image.
© 2007 JupiterImages.com
B We duplicated the image layer, then applied the Charcoal filter to the duplicate layer.
C The Charcoal filter is applied to a duplicate image layer.
- Choose the History Brush tool
(Y or Shift-Y). - On the Options bar:
Click the Brush Preset picker arrowhead, then click a brush on the picker.
Choose a blending Mode, Opacity percentage, and Flow percentage.
- On the History panel, click in the leftmost column for the state or snapshot to be designated as the source for the History Brush tool; the history source icon
moves to that slot.D
D To set the history source icon, we clicked in the leftmost column for a state prior to the filter edit but after the layer addition (in this case, it’s the state called “Layer Via Copy”).
- On the Layers panel, click the layer that you want to restore pixels to, and make sure Lock Transparent Pixels
is off. - Draw strokes on the image. Pixel data from the prior state of that layer will replace the current data where you apply strokes.A–C
A On the duplicate layer that we applied the filter to, we applied strokes with the History Brush tool (we chose an Opacity of 55% and a big scratchy Spatter brush for the tool).
© 2007 JupiterImages.com
B In the Layers panel for the final image (shown below), you can see that the original color was restored to some areas of the duplicate layer.
C Some of the original color is visible in this final image.
• Say you apply some brush strokes to a layer, then decide a few editing steps later that you want to remove them. If you click the state above the one labeled “Brush Tool,” the edits that you want to keep will be deleted when you resume editing. Instead, set the source for the History Brush tool as the state above “Brush Tool,” click the layer on the Layers panel that you applied brush strokes to, then with the History Brush tool, paint out your strokes in the document window.
The Fill command, when used with the History option, fills a layer or selection with pixels from a designated history state or snapshot. Our note on page 172 also applies to this command.
To fill a selection or layer with a history state or snapshot:
- Edit your document, and click an image layer.A
A This is the original image.
© 2007 JupiterImages.com
- Optional: Create a selection. You can either leave the selection edges sharp or use Refine Edge to feather them.B
B We applied the Conté Crayon filter to a duplicate image layer, selected the bottom area of that layer, then feathered the selection by using the Refine Edge command.
- On the History panel, click in the leftmost column for the state or snapshot you want to use as the fill data. The history source icon
will appear where you click.
- Choose Edit > Fill (Shift-Backspace/Shift-Delete). The Fill dialog opens.C
C In the Fill dialog, we chose Use: History. (You can also change the Blending Mode and Opacity, if desired.)
- Choose Use: History.
- Choose a Blending Mode and an Opacity percentage.
- Check Preserve Transparency to replace only existing pixels, or leave it unchecked to allow pixels to appear anywhere on the current layer. This option is available only if the layer contains transparent pixels.
- Click OK.D
D The selection is filled with the unedited imagery at an Opacity of 75%.
