Simple vision-correcting overlay and algorithm could replace reading glasses for viewing devices

July 30, 2014

A pinhole-array mask on top of an iPod touch (top and side views)  (credit: Fu-Chung Huang)

UC Berkeley and MIT researchers have developed a prototype of a simple vision-correcting display (and associated algorithm) that uses a printed pinhole screen sandwiched between two layers of clear plastic attached to an iPod display to enhance image sharpness.

The tiny pinholes are 75 microns (millionths of a meter) each and spaced 390 microns apart.

The algorithm adjusts the intensity of each direction of light that emanates from a single pixel in the display image and is based upon a user’s specific visual impairment. In a process called deconvolution, the light passes through the pinhole array in such a way that the specific user will perceive a sharp image.

“Instead of relying on optics to correct your vision, we use computation,” said lead author Fu-Chung Huang, who worked on this project as part of his computer science Ph.D. dissertation at UC Berkeley. “This is a very different class of correction, and it is non-intrusive.”

The UC Berkeley researchers teamed up with MIT colleagues Gordon Wetzstein and Ramesh Raskar to develop their latest prototype.

Fu-Chung Huang et al.| A proposed computational display architecture is evaluated in simulation and with a low-cost prototype device.

The technology could potentially help hundreds of millions of people who currently need corrective lenses to use their smartphones, tablets and computers. It could also one day aid people with more complex visual problems, known as high order aberrations, which cannot be corrected by eyeglasses, said Brian Barsky, UC Berkeley professor of computer science and vision science, and affiliate professor of optometry.

“We now live in a world where displays are ubiquitous, and being able to interact with displays is taken for granted,” said Barsky, who is leading this project. “People with higher order aberrations often have irregularities in the shape of the cornea, and this irregular shape makes it very difficult to have a contact lens that will fit. In some cases, this can be a barrier to holding certain jobs because many workers need to look at a screen as part of their work. This research could transform their lives, and I am passionate about that potential.”

The blurred image on the left shows how a farsighted person would see a computer screen without corrective lenses. In the middle is how that same person would perceive the picture using a display that compensates for visual impairments. The picture on the right is a computer simulation of the best picture quality possible using the new prototype display. The images were taken by a DSLR camera set to simulate hyperopic vision. (Credit: photo by Houang Stephane/flickr; modified by Fu-Chung Huang/UC Berkeley)

“In the future, we also hope to extend this application to multi-way correction on a shared display, so users with different visual problems can view the same screen and see a sharp image,” using eye-tracking technology, said Huang, now a Microsoft software engineer.

A paper (open-access preprint here) on the research will be published in ACM Transaction on Graphics and will be presented on Aug. 12 at SIGGRAPH in Vancouver, Canada. The National Science Foundation helped support this work.

Abstract of ACM Transaction on Graphics paper

Millions of people worldwide need glasses or contact lenses to see or read properly. We introduce a computational display technology that predistorts the presented content for an observer, so that the target image is perceived without the need for eyewear. By designing optics in concert with prefiltering algorithms, the proposed display architecture achieves significantly higher resolution and contrast than prior approaches to vision-correcting image display. We demonstrate that inexpensive light field displays driven by efficient implementations of 4D prefiltering algorithms can produce the desired vision-corrected imagery, even for higher-order aberrations that are difficult to be corrected with glasses. The proposed computational display architecture is evaluated in simulation and with a low-cost prototype device.