fgbg-sep
The --fgbg-sep switch is off by default. If you turn it on, then it forces segmentation of image-only ("scanned image") PDF pages.
Image-only PDF pages are typically created by scanner applications. The
use of this switch causes such pages to be segmented. The alternative is to
have them photo-encoded. The segmenter has many switches, which can be adjusted
by using the --profile switch.
Please note that the --fgbg-sep
switch may
harm the quality of photo pages.