How does the iPhone's Portrait Mode figure out what part of your picture is the subject and what is the background to blur it?

The iPhone's Portrait Mode identifies the subject and background to apply a selective blur, mimicking the shallow depth of field of a professional camera, through a combination of advanced hardware and sophisticated machine learning algorithms. Its ability to sense depth varies by model. Older iPhone models with two rear cameras, for example, capture two slightly different perspectives of the same scene simultaneously, similar to how human eyes perceive depth. By analyzing the tiny differences in position (known as parallax) between corresponding points in these two images, the iPhone calculates the relative distance of objects in the scene. Objects that appear to shift more between the two views are closer to the camera, while those that shift less are farther away. Newer iPhone Pro models incorporate a LiDAR Scanner, which stands for Light Detection and Ranging. This scanner emits invisible l....