As an imaging processing veteran with a keen observational eye, I sometimes forget that not everybody catches the same things I pick up on. For example, I consistently spot the neighborhood Kestrel at 200 yards – which most people never see. It is a small bird.
This is what I see. In frame 317, John Connally’s bald forehead is facing forwards and reflecting the sun. The right side of Kennedy’s head looks very different.
Connally’s forehead shows a typical reflection off a convex surface. Elliptical, brightest near the middle, and the luminosity tails off towards the edges. His head is facing towards the sun. There is also a vertical shadow in the middle of the reflection, possibly a light pole.
The circle on JFK’s head, looks very different. It is quite round, and has bright consistent luminosity across the entire circle. It is surrounded by dark hair which is shaded. There is no indication that side of his head is receiving direct sunlight. The luminosity is higher than anywhere on Connally’s forehead.
This is clearly a light source, not a reflection. And it remains consistent for a few dozen frames.