Smart glasses dim bright objects but don’t affect other things in view

By Matthew Sparkes

2 May 2023

Glasses that dim bright objects by restricting light in selective parts of the field of view

Xiaodan Hu/Nara Institute of Science and Technology

Smart glasses fitted with a camera and LCD screens can “balance” a scene by dimming the brightest objects and leaving dim ones unchanged. The device could help people affected by photophobia, who experience pain or discomfort from intense light.

Such people can simply wear sunglasses, but they alter their whole field of view and make darker areas difficult to see. The new glasses, developed by Xiaodan Hu at Nara Institute of Science and Technology, Japan, and her colleagues, dim only parts of the scene that are overly bright.

They work by feeding the input from a camera through a small computer which “balances” the image by running an algorithm that dims the brightest areas. The wearer sees the scene through transparent LCD screens, which look like the lenses of spectacles, but which can adjust how much light passes through each pixel of the screens based on the computer’s output.

The system takes just 20 microseconds to adjust to changing light conditions, meaning that even rapid transitions appear seamless.

Previous studies using similar technology have attempted to block specific areas of a view while allowing the rest of the scene to be visible through a transparent screen, but the human eye can’t focus on the blocked parts of the screen while also looking at the rest of the distant scene, resulting in a blurred image. Hu’s approach avoids that problem by rendering the entire image on a single screen, with areas of pixels only serving to dim the natural light, not replace it.

Hu says that the glasses could be miniaturised to look like normal glasses and that the current system costs around $900 per pair, but this would fall if produced at scale.

“For photophobic individuals, the system allows them to wear sunglasses at all times without fear of being bothered by either sunlight or fluorescent lights,” says Hu. “In addition, the general public can use them while driving or cycling for added comfort and safety.”