Image Quality of a Mobile Display under Different Illuminations

Abstract

This study constructed the image quality models for a small mobile display under different ambient illumination levels using Group Method and Data Handling (GMDH) and described the relationship between perceived image quality and physical measurements. 33 college students took part in this experiment and were asked to evaluate the image quality under 1500 lux (typical indoor office illumination) and 7000 lux (simulated outdoor environment) in Stage One and Stage Two, respectively. In each stage, the participants had to evaluate 21 images. 17 sets of the data as a training set were used to build the model and four sets of the data as a testing set were used to verify the model. The results indicated that the effects of luminance, contrast, correlated color temperature (CCT), and resolution were significant on perceived image quality under 1500 lux. However, color temperature was not a significant physical characteristic, and an interaction between luminance and contrast was found below 7000 lux. From the results of the experiment, it is considered that the outdoor environment (7000 lux) is not suitable for using mobile displays. Finally, once a valid image quality model is built, the subjective image quality can be established when the measurements of significant physical characteristics are provided. The results of subjective ratings can also be provided for mobile display manufacturers to improve the product quality so that their products can meet customers' requirements.

The Effect of Ambient Illumination on Handheld Display Image Quality

“…Because of the expanded illuminance range, we are able to more accurately determine the perceptual limits on mobile displays. Lin and Kuo determined that environments around 7,000 lx are not suitable for using handheld displays [6]. In addition to supporting this claim, our data suggests that in environments over 1,000 lx, user performance begins to decline at a faster pace, with most users only achieving near 50 % correct in our text detection test and noticeably worse as the environment illuminance increases.…”

“…In a recent report by Lin and Kuo [6], the authors studied the image quality of a handheld display device under different ambient illumination levels. Considering the physical characteristics of color temperature, luminance, contrast, and display resolution, Lin and Kuo concluded that outdoor environments around 7,000 lx are not suitable for handheld displays.…”

It's not just the light

“…Most modern mobile devices have transmissive displays, which emit (as opposed to reflect) light [5], using either filtered backlighting or colour LEDs to produce an image. Due to the limited light production abilities of these displays, perceived image quality worsens as ambient light increases [25,26,30]. Other solutions for brighter displays have been introduced, such as Nokia's ClearBlack Display [14] and the One Glass Solution [20].…”

Designing for Situational Visual Impairments

“…The typical transmissive displays used in mobile devices require a backlight to display content on the screen [7]. Increasing ambient light reduces the image quality on the display [26,25,30] and the issue remains with newer screen technology, such as IPS and AMOLED displays [18]. Although anti-glare layers help, they can degrade image quality [40] and cause users to experience "visual sparkle", which is a perceived glittering effect on the display [8].…”