The ability to read imaging studies on portable devices declines when those devices are used in ambient light conditions rather than average office conditions, according to a study published in the October issue of the Journal of Digital Imaging.
According to the researchers, led by Peter Liu, because of the reflectivity of handheld devices, performance deteriorates the farther the user moves from darker areas into environments of great ambient illumination.
In the study, three subjects were asked to detect and distinguish four objects that were embedded in a white-noise background in conditions simulating dark room, office, and outdoor conditions. Observers performed best at detecting items in dark conditions, while bright conditions presented them with more difficulties.
As reported in an article in AuntMinnie.com, the authors wrote "the data confirms that there is a negative correlation between illuminance and user performance for each device. A larger sample of observers would be needed in order for this trend to be more definitive."
The authors pointed out that a previous study had found that environments with ambient lighting of more than 7,000 lux aren't suitable for reading handheld displays. For this study, the researchers found that in environments over 1,000 lux (which represents a medium-bright outdoor environment) user performance starts declining "at a faster pace, with most users only achieving near 50 percent correct in our text detection test and noticeably worse as the environment illuminance increases." Consequently, anything with an illumination greater than 1,000 lux might not be an optimal environment for radiologists to read images.
The researchers also determined screen reflectivity was a major factor in decreased reading performance, meaning that in general, the authors wrote, devices with higher reflectivity may not be optimal for reading images.