Photoshop History Palette
In photoshop the history palette records almost every step you make when editing in Elements. It lets you undo the changes and step back through recent changes. At any time, you can click on an earlier state and remove the changes you made. This allows multiple undo.The undo command undoes only the last performed operation, while the history palette lets you undo a series of tool operations or commands. To open the history palette, choose window> Show History.
|In the history palette each state is listed with the name of the tool or command used to change the image, with the oldest state at the top of the list followed by more recent states.
Click the snap shot at the top of the list to display the state of the image when you first opened it. You can also use the File > Revert command to reverse all the changes made.
You can select a state from the history palette and continue editing the image from that state. Then all the states that come after the selected one are eliminated by default.For eg. in the above fig, suppose you selected the state ‘ Rectangular marquee ‘ and used a paint brush to paint. Then the states come after ‘ Rectangular marquee ‘( ie. paintbucket, stroke and deselect) are deleted. You can select the allow Non-Linear History option to make changes to a selected state without deleting subsequent states. (For that click the right arrow in the top and select history options…)
You can set the number of states available. For that click the right arrow in the top and select History options and enter the number. Once you have done more edits than you have history states set, the oldest edits are eliminated from History as new edits occur. Remember that each brush stroke, and each mouse click with a tool is one edit. If you think you may need to step back in history (use multiple undo), keep an eye on you history states.
Note the little tab on the extreme left end of the last state (the dark blue state). Drag on this to return to earlier states. This can be fun to play with it will scroll your image backwards like a movie in reverse. Drag it forward again to watch the movie the other way.
History is not saved once you close the document.