- Using the main application features
- Using the panels
- Tools on the Tools panel
- Changing the image size
- Choosing a bits per channel mode
- Cropping and rotating images
- Using the Layers panel
- Creating adjustment layers
- Editing adjustment layers
- Limiting the effect of an adjustment layer
- Saving adjustment presets
- Merging and deleting adjustment layers
- Working with layer groups
- Applying content-aware scaling
- Choosing a mode for the History panel
- Making snapshots of history states
- Working with nonlinear histories
- Using presets
- Streamlining your workflow
Choosing a mode for the History panel
Whenever you work on a document, your edits are automatically listed as states on the History panel (whether the panel is displayed or not).A Via the History & Cache: History States setting in Edit/Photoshop > Preferences > Performance, you can specify the maximum number of states that the panel may list. If this number is exceeded, prior states are deleted to make room for the new ones. Each open document has its own list of states, but they will remain on the panel only until the document is closed.
A fast way to undo multiple edits is by clicking a prior state on the History panel. You can work with the panel in either of two modes. To change modes, choose History Options from the panel menu, then check or uncheck Allow Non-Linear History. With the panel in linear mode (Allow Non-Linear History unchecked), if you click an earlier state and resume editing from or delete that state, all subsequent (dimmed) states are discarded. Simple.
In nonlinear mode, if you click (or delete) an earlier state, subsequent states aren’t deleted or dimmed. In this mode, if you resume image editing with an earlier state selected, your next edit will show up as the latest state on the panel. This latest state will incorporate the earlier stage of the image plus your newest edit, and all the states in between will be preserved. If you change your mind, you can click any in-between state whenever you like and resume editing from there. To learn more about this mode, see pages 108–110.
- The Make Layer Visibility Changes Undoable option in the History Options dialog causes the clicking on or off of a visibility icon on the Layers panel to register as a history state. If you want to prevent this from happening (so those states don’t take up needed space on the panel), keep this option off.
- To undo an unintentional file save, click a pre-Save state on the History panel.