The scene mode which uses HDR technology is the "Backlight Correction HDR", see
http://www.iliketheinternet.com/HX100V/contents/06/02/03/03.html
"Allows you to shoot three images having different exposures to create a single image with a greater range of gradation. The camera combines the dark parts of an image taken with a bright exposure setting and the bright parts of an image taken with a dark exposure setting."
There is no separate D-Range Optimizer (DRO setting, known from Alpha, Nex and some previous cybershot).
in iAUTO+ mode the camera may choose the HDR mode, which is indication by the sun+ icon.
Message was edited by: cmosse