Olympus is apparently using an amalgam of both techniques for HHHres. As it has been described (and most reviewers’ explanations get fuzzy at this point), IBIS gets turned off for a short period of time, the photo is captured and then IBIS gets turned back on, then the process repeats itself. It sounds like Olympus uses the handheld shakiness to move the sensor slightly, and the IBIS limits how much movement is allowed to occur over the course of the captured images. The camera takes 16 shots and combines them for one result.