The Evolution of Image Sensors Toward the Human Eye: Samsung Semiconductor’s Innovative Dual Pixel Pro Technology

Samsung recently introduced ISOCELL GN2, another innovative image sensor for pro-grade smartphone cameras. ISOCELL GN2 offers greatly improved autofocus using Dual Pixel Pro technology, which features diagonally divided pixels for the first time in the industry. Let’s take a closer look at the technologies behind this image sensor that rivals the human eye. Special Autofocus Pixels Used in PDAF Technology To understand how Dual Pixel Pro works, it is important to first understand its foundational technology, Phase Detection Autofocus (PDAF). Just like how humans use their two eyes to focus, PDAF compares the phase difference perceived from two different locations and moves the lens such that the two phases align to adjust the focus.

Conventional PDAF systems use special, dedicated autofocus pixels embedded throughout the sensor. Half of each autofocus pixel is blocked so that phase differences between the left-looking and right-looking images can be compared. Using a larger number of these dedicated autofocus pixels can make phase detection faster but can also result in loss of image quality because these pixels cannot receive color information. This made us wonder: can we make autofocus faster and more accurate without sacrificing image quality? Is it possible to create pixels that can help with autofocusing and receive color information at the same time? Starting from these questions, Samsung developed Dual Pixel technology by improving upon PDAF. Dual Pixel with Improved Autofocus

Each pixel on a Dual Pixel sensor contains two photodiodes, one left-looking, one right-looking. When capturing a scene, the phases from each pair of photodiodes are compared to achieve autofocus. Since every pixel in the sensor is being used for both autofocus and color values, the sensor can achieve quick autofocus without losing image quality. Dual Pixel Pro with Innovative Pixel Design What are the main differences between Dual Pixel and Dual Pixel Pro, which is available in the recently released ISOCELL GN2?

In the previous Dual Pixel technology, each pixel is divided vertically into left and right. Dual Pixel Pro features green pixels that are divided diagonally. There are clear benefits in dividing pixels diagonally. These pixels can compare the phase differences between the top and bottom of the pixel in addition to phase differences in the left and right sides. As a result, even in a situation where autofocusing is challenging to achieve based on the use of only left and right phase differences, Dual Pixel Pro can use top and bottom phase differences, therefore delivering faster and more accurate autofocusing capabilities.