Raymond Soneira, the president of DisplayMate, selected five phones and four tablets, and subjected them to various levels of light intensity. the idea, he said, was to simulate the various light levels as a user walked with his phone or tablet from the dark outside to a sunlit area.
Soneira summarized his findings in a report published on the DisplayMate website.
“While the displays all look about the same in the dark, as the ambient lighting levels increase, particularly outdoors, there are dramatic differences in screen viewability, which depend on a combination of each display’s inherent screen brightness and screen reflectance,” Soneira wrote. “It’s important because mobile devices are seldom used in the dark.”
Contrast ratio, one of the display metrics that some display makers tout, means little in strong ambient light, Soneira noted. He tested from 0 lux, or absolute darkness, through seven gradations of ambient light up to 40,000 lux, or the equivalent of indirect outdoor sunlight.
Soneira said that when the tested displays were exposed to stronger intensities of light, they typically showed an increase in brightness for what should have been a perfectly black background. Color saturation faded, too. And although Soneira didn’t specifically address it, phones typically adjust the brightness of a display upwards in strong light, lowering the battery life of the phone.
the phone with the best display under ambient light conditions was the Lumia 900, which Soneira assigned a high-ambient-light (HAL) contrast ratio score of 90. the Samsung Galaxy S and Apple iPhone 4 finished second and third with HAL scores of 80 and 77, respectively. the Motorola Droid X and HTC Desire finished fourth and fifth with scores of 20 and 15, respectively, indicating that their displays essentially vanished under bright lights.
Soneira found that the Samsung Galaxy Tab 10.1 produced the highest contrast rating, or 57, in the brightest light. under those conditions, the displays on even the best-performing phones and tablets were almost entirely washed out. the new Apple iPad ranked second, although Soneira said he didn’t include the display screenshots in his report page, and didn’t assign the tablet a score. the iPad 2 finished third, with a score of 47, followed by the Amazon Kindle Fire (24) and the Motorola Xoom (20).
Soneira didn’t bother testing at the equivalent of direct sunlight at noon, or 100,000 lux. those are the conditions for which e-readers using e-ink, such as the original Amazon Kindle or Barnes & Noble Nook, were designed.
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