Video demonstrating the benefits of Nokia's new version of their sunlight readability enhancement mode on the Lumia 1520. The new technology is based on Apical's Assertive Display technology, which allows a pixel-by-pixel adjustment of what is being displayed on screen based on what is being displayed and in what lighting conditions.
You'll notice the biggest impact in bright light (e.g. sunshine), especially when viewing photos, videos, and other colourful content.
Nokia's previous version of sunlight readability enhancement mode did something similar, but across the whole screen (not pixel by pixel), which meant the screen could appear washed out.
Combined with Nokia's other screen technologies (High brightness mode, ClearBlack,
Lumia Color profile) and a high quality IPS-LCD screen (1080p resolution) this gives the Lumia 1520 one of the best screens available on any smartphone.
More at http://allaboutwindowsphone.com/features/item/18648_Video_Sunlight_readability_enh.php