Epson Perfection V500 - Manual (Page 79)

If you are going to scan your image to a particular size, you should select the Target Size setting
after previewing it, but before adjusting your scan area (indicated by the marquee). This sets
the scan area to the correct proportions so your image will not be cropped unexpectedly.
For instructions on previewing your image(s), see Previewing and Adjusting the Scan Area . Then
follow these steps to select the Target Size setting.
You can choose a predefined scan size from the Target Size list. Click the arrow in the list
and select the size you want. A marquee (dotted line) proportioned for that size appears
on your preview image.