Epson GT-6500 EN - Manual (Page 33)

Scanning area
The maximum scannable area for each scanner is determined by the
physical dimensions of the document table. You can also use
commands to tell the scanner to scan only a certain portion of your
document.
You set the scanning area in units of pixels. First set the point to begin
scanning, and then set the number of pixels beyond that point you
wish to scan.
Since you set these values as the number of pixels, using the zoom
function or changing the resolution affects the physical size of the
scanning area.
Overview 1-19