Background Blur
An image processing technique that applies blur to the background while keeping the subject sharp, simulating the bokeh effect of wide-aperture lenses.
Background blur is a technique that keeps the main subject sharp while applying blur to the background, making the subject stand out prominently. It digitally replicates the bokeh effect naturally produced by wide-aperture lenses on DSLR cameras.
Smartphone portrait modes use dual cameras, depth sensors, or similar means to separate the subject from the background, then blur the background. Some devices let you adjust blur intensity in the form of f-stop values.
To blur backgrounds after capture, one approach is using the background removal tool to isolate the subject, then compositing it over a separately blurred background. A related optical concept is depth of field.