Down Imaging in the HB SI xx7 series units was offered as a software update in early 2010 somewhere around version 4.750...
As the 997 was introduced before this update...the software version in the unit will dictate if that specific unit has the Down Imaging feature...
The software version in the unit can be verified by pressing Menu during the startup splash screen ...and then choosing the System Status selection from the popup window....
Because new models come out fairly frequently...and software updates come out even more frequently...it is unlikely the user manual for the 997 was updated to include the Down Imaging feature verbiage...
Rickie