Changing the Onscreen Display Size of a Digital Photo with Adobe Photoshop Elements
For onscreen photos, pixel count (resolution) determines the display size of the picture. If you want to change the display size of a digital photo, you must either add or remove pixels from the image file. (Note that adding pixels, while increasing the display size, can also degrade picture quality.) To change the pixel count in Adobe Photoshop Elements, take these steps:
Select Image→Resize→Image Size.
The Image Size dialog box appears.
Select the Resample Image and Constraint Proportions boxes and enter the new pixel dimensions in the Width and Height boxes at the top of the dialog box.
You only need to enter either the width or height — after you do, the program automatically enters the other dimension for you.
Choose File→Save As and save the file with a new name.
The Save As dialog box appears. Be sure to give your resized file a new name; you don’t want to overwrite the existing file because you may need your original pixel count someday.
Do not use this process to change the print size of a picture. Instead, uncheck the Resample Image box and then set your print size using the Document Size boxes.