The History palette in Photoshop Elements offers another way for you to step backward and forward through the editing steps you've taken. At the top of the palette is a small thumbnail icon and the file name of your image. Whenever you open an image, Photoshop creates a "snapshot" of the original state of the image and shows it at the top of the history palette. A quick way to revert your image is to click this initial snapshot. It's also useful for quickly comparing a before and after view of your editing.
Below the original state thumbnail, you'll see a list of all the recent changes you have made to the image in chronological order from top (oldest) to bottom (most recent change). The list shows the tool or command you used to change the image so you can see exactly what you've done. You can undo any of these recent changes just by clicking the last change you want to revert to, or by dragging the small slider that appears next to each state. The slider is useful if you're not sure how far back you need to go because it allows you to preview the changes as you move it up or down.
By default, Elements lists the last 50 actions you have performed on an image. Anything older is purged from the list to allow more memory for Elements. If you have plenty of memory, you can increase this number by going to Edit > Preferences > General and typing a higher number into the box for History States. Or you can reduce the number if you're low on memory. You can also purge the history list as-needed by using the "Clear Undo History" command in the history palette's menu. Note, however, that this action is irreversible.
Here are a few more important points about Undo History:
- History is not saved with an image. Closing an image will clear all history from your working session.
- Reverting to a previous state and then editing your image eliminates all history states that had come after it.
- Deleting a state deletes everything after it.