Correcting for optical aberrations using multilayer displays

Abstract

f r o n t l a y e r r e a r l a y e r wa t c h f a c e c o r r e c t e d f o r p r e s b y o p i a c o n v e n t i o n a l d i s p l a y s i n g l e -l a y e r p r e -f i l t e r i n g t wo -l a y e r p r e -f i l t e r i n g p e r c e i v e d i ma g e s d i s p l a y e d i ma g e sFigure 1: Correcting presbyopia using multilayer displays. A presbyopic individual observes a watch at a distance of 45 cm. The watch appears out of focus due to the limited range of accommodation. To read the watch, corrective eyewear (e.g., bifocals) must be worn with a +2.50 diopter spherical lens. (Left) As a substitute for eyewear, the watch can be modified to use a multilayer display containing two semi-transparent, light-emitting panels. The images displayed on these layers are pre-filtered such that the watch face appears in focus when viewed by the defocused eye. (Right) From left to right along the bottom row: the perceived image using a conventional display (e.g., an unmodified LCD), using prior single-layer pre-filtering methods, and using the proposed multilayer pre-filtering method. Corresponding images of the watch face are shown along the top row. Two-layer pre-filtering, while increasing the watch thickness by 6 mm, enhances contrast and eliminates ringing artifacts, as compared to prior single-layer pre-filtering methods. (Watch image c Timex Group USA, Inc.) AbstractOptical aberrations of the human eye are currently corrected using eyeglasses, contact lenses, or surgery. We describe a fourth option: modifying the composition of displayed content such that the perceived image appears in focus, after passing through an eye with known optical defects. Prior approaches synthesize pre-filtered images by deconvolving the content by the point spread function of the aberrated eye. Such methods have not led to practical applications, due to severely reduced contrast and ringing artifacts. We address these limitations by introducing multilayer pre-filtering, implemented using stacks of semi-transparent, light-emitting layers. By optimizing the layer positions and the partition of spatial frequencies between layers, contrast is improved and ringing artifacts are eliminated. We assess design constraints for multilayer displays; autostereoscopic light field displays are identified as a preferred, thin form factor architecture, allowing synthetic layers to be displaced in response to viewer movement and refractive errors. We assess the benefits of multilayer pre-filtering versus prior light field pre-distortion methods, showing pre-filtering works within the constraints of current display resolutions. We conclude by analyzing benefits and limitations using a prototype multilayer LCD.

Image Pre-compensation: Balancing Contrast and Ringing

“…Specifically, we provide a simple user interface to trade between ringing and contrast that allow user to adjust the ringing control factor for generating the optimal curve. Our user study shows that our technique is effective and comparable to the state-ofthe-art solutions [1,9] in both visual quality and quantitative measures.…”

“…The phenomena of significant dynamic range stretch in image deconvolution has been widely documented in signal processing [22] and computer graphics/vision literature [26,1,8,9]. To briefly reiterate, the stretch is due to matrix inversion.…”

“…To enhance contrast, Pamplona et al [20] designed a special computational display using multiple layers of LCDs. Huang et al [9] later developed a multi-layer pre-filtering on an ultra-high dynamic range light field display. All these solutions use simple tone mapping functions and rely on the displays to enhance contrast.…”

Eyeglasses-free display

“…Multilayer Display [Huang et al 2012] (prefiltering) [Pamplona et al 2012] (no processing) (prefiltering) (Source image courtesy of flickr user dfbphotos)…”

“…Light field displays offering such capabilities require extremely high angular sampling rates, which significantly reduce spatial image resolution. As a high-resolution alternative, Huang et al [2012] proposed a multilayer device that relies on prefiltered image content. Unfortunately, the required prefiltering techniques for these particular optical configurations drastically reduce image contrast.…”