Seconding that file format is the important element here. Likely the maps are in an image file format that Laserfiche has a default configuration to compress. The contents of the images aren't relevant here to the setting, jus the file type.

As an immediate workaround that doesn't require any configuration changes, you could append a ".map" (fake) file extension to the map images before uploading them, as the ".map" extension is definitely not in Laserfiche's default list of image file formats and wouldn't trigger image compression. 

E.g., "large-map.jpg.map"

However, for the same reason you wouldn't be able to view the image in the Laserfiche document viewer as it doesn't know how to display ".map" files. A better problem that having the map images compressed though.

When you need to print a map, download it locally, remove the ".map" extension, and print.