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In recent years, warfighters have been using augmented reality (AR) displays in various operations. But while these displays work well indoors, the icons disappear outdoors because the displays have limited brightness. Even at the brightest level, they’re up to 100 times dimmer than a bright sunny day, so the icons and target highlights become invisible, decreasing warfighter performance.

Making the displays brighter is challenging due to the amount of power needed and it’s hard to make sure the highlighting isn’t so strong that it prevents the Soldier from paying attention to the rest of the scene.

Researchers from the U.S. Army Combat Capabilities Development Command, now known as DEVCOM, Army Research Laboratory discovered a new technique for AR to overcome bright lighting conditions during the day by using low contrast dimming highlights. They said this opens up new research questions that will improve warfighter AR and heads-up display performance in outdoor operations, according to army.mil.

Dr. Chou Hung, a neuroscience researcher at the lab, said: “We proposed a new approach, low contrast dimming, that can be used to titrate the visibility of target highlighting, but we were concerned that strong lighting variations on the retina as we shift our gaze would drown out the signal,” Hung said. “Our research shows that it should work; our visual system is actually very resilient to strong luminance dynamics; we can see very low contrast (10%) immediately after looking at something 100 times brighter.”

Researchers said future warfighters will need AR in outdoor and mixed indoor/outdoor environments. “Our discovery paves the way towards enabling that use, including in challenging desert, snow, marine, and dense urban environments,” Hung said. “The same approach could also improve situational awareness for other display technologies such as image intensifiers, infrared and fused night vision displays. This approach would also enable indirect optics and has potential for laser eye protection as well.”

The researchers studied high dynamic range, or HDR, luminance – images in which the brightest and darkest pixels differ by up to 100,000-to-1 ratio in brightness – and how it affects visual processing. Success will also make future commercial AR more functional in daytime environments, such as in snow sport settings.

The results were published in the Journal of Perceptual Imaging.