The phone's portrait mode simulates a bokeh blur effect.
Tips
usage
Photography jargon for out-of-focus blur - the 'bokeh' effect. Often said as 背景虚化 (background blur). Linguistically 虚化 also has a separate meaning in linguistics ('grammaticalization'), but that's a niche technical sense.
memory
虚 means 'empty/unreal' and 化 means '-ify/to turn into.' So 虚化 literally means 'to make (something) unreal/hazy' - a perfect description of defocused blur.
