SharpView: Improved clarity of defocused content on optical see-through head-mounted displays

Augmented Reality (AR) systems, which utilize optical see-through head-mounted displays, are becoming more common place, with several consumer level options already available, and the promise of additional, more advanced, devices on the horizon. A common factor among current generation optical see-through devices, though, is fixed focal distance to virtual content. While fixed focus is not a concern for video see-through AR, since both virtual and real world imagery are combined into a single image by the display, unequal distances between real world objects and the virtual display screen in optical see-through AR is unavoidable. In this work, we investigate the issue of focus blur, in particular, the blurring caused by simultaneously viewing virtual content and physical objects in the environment at differing focal distances. We additionally examine the application of dynamic sharpening filters as a straight forward, system independent, means for mitigating this effect improving the clarity of defocused AR content. We assess the utility of this method, termed SharpView, by employing an adjustment experiment in which users actively apply varying amounts of sharpening to reduce the perception of blur in AR content shown at four focal disparity levels relative to real world imagery. Our experimental results confirm that dynamic correction schemes are required for adequately addressing the presence of blur in Optical See-Through AR. Furthermore, we validate the ability of our SharpView model to improve the perceived visual clarity of focus blurred content, with optimal performance at focal differences well suited for near field AR applications.