Using the Fit Image Command
The Fit Image command is a quick way to adjust an image to a specific width and height without changing its current aspect ratio. While the same process can be accomplished using Photoshop's Image Size dialog box, this way is quicker and works more reliably when used to change the size of an image within an action. Like another one of the Automate commands called Conditional Mode Change, the Fit Image command is designed to work best when incorporated into an action. When the action is executed, the Fit Image command will adjust the image's size without opening any dialog boxes, or requiring you to answer any formatting questions.

Use the Fit Image Command
Open a document.
Click the File menu, point to Automate , and then click Fit Image .
Enter a Width and Height for the transformation.Photoshop maintains the image's aspect ratio.
Click OK .[View full size image]