Oooh that sounds technical and complicated doesn’t it! In essence, this is how you can get that cool many rayed star effect *without* having to spend money on a fancy filter. If you have a bright light spot (like the sun or street lights in the dark) and you crank the aperture up to F22 the camera does it for you like this. That bright light spot is the specular highlight.
The sun is just beginning to hit the horizon, and I found it needs to be partially obscured for this effect to work properly, but there you go. All for free!
Image shot incamera as you see it and output as a jpg with no further processing other than cropping
Learning to See Light 