That is, a sine wave with a period equal to the size of the box will be blurred away entirely, and wavelengths shorter than the size of the box may be phase-reversed, as seen when two bokeh circles touch to form a bright spot where there would be a dark spot between two bright spots in the original image.
That is, a sine wave with a period equaling the box's size will be entirely blurred away, and wavelengths shorter than this size could experience phase inversion. This phenomenon can be seen when two bokeh circles touch to produce a bright spot where there would have been a dark spot in the original image.