Canon PIXMA MG4200 Series On-Screen Manual page 671

If you select Magazine (Color), the descreen function will be active.
Display Preview Image
Preview
Performs a trial scan.
Note
When using the machine for the first time, scanner calibration starts automatically. Wait a while
until the preview image appears.
Destination
Select what you want to do with the scanned image.
Print
Select this to print the scanned image on a printer.
Image display
Select this to view the scanned image on a monitor.
OCR
Select this to use the scanned image with OCR software.
"OCR software" is software that converts text scanned as an image into text data that can be
edited in word processors and other programs.
Output Size
Select an output size.
Output size options vary by the item selected in Destination.
Flexible
Allows you to freely adjust the cropping frames (scan areas).
In thumbnail view
Drag the mouse over a thumbnail to display a cropping frame. When a cropping frame is
displayed, the portion within the cropping frame will be scanned. When no cropping frame is
displayed, each frame is scanned individually.
In whole image view
When no cropping frame is displayed, the entire Preview area will be scanned. When a cropping
frame is displayed, the portion within the cropping frame will be scanned.