From the Finder desktop, double-click the Lexmark 3500-4500 Series folder.
Double-click the Lexmark 3500-4500 Series Center icon.
From the All-In-One Center, click Preview/Edit to open the Scan dialog.
Click to open the Scan Settings drawer.
Select the Adjustments tab.
From the Brightness area, move the slider to lighten or darken the image.