I thought about a filter that would stick on your window, to block glare from your side mirrors.
Use two disks of polarized film. When the brightness off the mirror spikes, rotate one disk to reduce the amount of light transmitted. Once a sensor notes that the mirror is no longer reflecting someone's too-bright headlights, it would rotate the disk back to maximum light transmission.
The area involved could be pretty small, and most of the view through the window and mirror would be unaffected.
That is basically a crude description of how LCD displays work - polarized layers, one of which can be selectively rotated to control how much light comes through.
Right. I just figure a coupla pieces of polarized film would be cheaper, simpler, and more flexible (physically) than an LCD. (Since car interiors and glass tend towards curvy rather than flat, a flexible film would likely be more workable than an LCD panel.)
Use two disks of polarized film. When the brightness off the mirror spikes, rotate one disk to reduce the amount of light transmitted. Once a sensor notes that the mirror is no longer reflecting someone's too-bright headlights, it would rotate the disk back to maximum light transmission.
The area involved could be pretty small, and most of the view through the window and mirror would be unaffected.