Ambient light sensors built into the borders around the screen, or in pricier border-less handsets – underneath the screen itself, measure the amount of light around you and adjust the brightness. This is designed to preserve battery life, while still ensuring that you can read everything on-screen when looking at your phone in direct sunlight.
So, that all makes sense on a smartphone... but what is the point in a 4K OLED set? While there might not be any battery life to preserve, Samsung says the technology will enable its Smart TVs to adjust the picture to ensure optimum viewing in all light conditions.