The Effect of Ambient Illumination on Handheld Display Image Quality

Abstract

Handheld devices such as smartphones and tablets are becoming useful in the medical field, as they allow physicians, radiologists, and researchers to analyze images with the benefit of mobile accessibility. However, for handheld devices to be effective, the display must be able to perform well in a wide range of ambient illumination conditions. We conducted visual experiments to quantify user performance for testing the image quality of two current-generation devices in different ambient illumination conditions while measuring ambient light levels with a real-time illuminance meter. We found and quantified that due to the high reflectivity of handheld devices, performance deteriorates as the user moves from dark areas into environments of greater ambient illumination. The quantitative analysis suggests that differences in display reflection coefficients do not affect the low illumination performance of the device but rather the performance at higher levels of illumination.

It's not just the light

“…Other solutions for brighter displays have been introduced, such as Nokia's ClearBlack Display [14] and the One Glass Solution [20]. However, improved screen technologies are still susceptible to reduced brightness and contrast when viewed under bright ambient lighting [19,31], and focusing on bright ambient lighting only addresses one cause for SVIs. Reducing screen brightness to conserve power creates a similar problem to viewing a screen in a bright environment.…”

“…Mobile devices are recognised as useful tools in the workplace, but mobile devices need to be adaptable for different situations [1]. Safety concerns have led to investigations into the degree to which ambient light levels affect image quality on mobile displays, such as in medical settings [31,61].…”

Designing for Situational Visual Impairments

“…Mobile device screens are difficult to use as ambient light intensity increases [18]. As a result, recent research has questioned the suitability of mobile devices in medical settings due to SVIs [31]. In general day-to-day use, common design choices, such as Apple's use of low-contrasting font, introduces new challenges and this has been criticised for making reading difficult for people with typical vision [39].…”

Auto-brightness control technology depending on user’s pupil area

“…A study has shown that visual performance of displays can be improved when the luminance or contrast ratio becomes higher [8]. In addition, there are studies on the image quality due to the reflection of the glass of the LCD top plate along with the ambient illuminance [9,10]. However, a dynamic visual information processing task of LCD and OLED display can induce visual fatigue and both temporal and environmental factors affected visual load [11].…”