Canon MX390 series Online Manual page 115

Slight cropping may occur at the edges since the copied image is enlarged to fill the whole
page. You can change the width to be cropped from the borders of the original image as needed.
However, the cropped area will be larger if the extension amount is large.
For details:
Extended copy amt.
For details on the paper size and the media type available for borderless copying:
Printing Area