Which way does JFK’s head move from Frame 312 to Frame 313 of the Zapruder Film?

Incredibly, in 2021, nearly 58 years after the assassination, a newly-published book led to this question still being debated. I answered it comprehensively 20 years earlier, in 2001—for the author of that very same new book! Here I answer it anew using current image processing programs.

Most rigorous method: blur Frame 312 the same as Frame 313

As I show on this page, it is straightforward to use a blurring program to blur Frame 312 in approximately the same manner that Frame 313 is blurred. Flipping between the two blurred frames gives us an immediate answer:

Frame 313 v Frame 312 blurred by the deduced blur of Frame 313

It is undeniable that JFK’s head moves forwards from Frame 312 to Frame 313. The exact amount of forward movement (in inches) would depend on which part of his head is being referenced, as his head clearly rotates forwards on his neck.

Clearer to see method: deblur Frame 313

Again, as described on this page, one can use a deblurring program to estimate what Frame 313 would have looked like if it was not motion-blurred. This method is not as rigorous as that above, since deblurring is not in general uniquely defined for an image in the presence of noise. For the purpose of answering the question of which way JFK’s head moved, it is most useful to take Frame 312 (properly rotated and aligned) as the initial approximation, and then run the deblurring algorithm to remove, as best possible, any inconsistencies between that and the blurred Frame 313. Flipping between the resulting image and Frame 312, we see this:

UnBlurred Frame 313, using Frame 312 as an initial approximation, v Frame 312

As noted on that other page, the red spray at the front of his head cannot be well-modeled by the assumption of camera motion-blurring of an object stationary in the limo, since the red spray would not have been stationary. In addition, remnants of JFK’s right ear and nose remain in the deblurred image, surviving from the initial approximation image, which should not be taken to represent real detail in the deblurred image, but merely as detail that has been “dropped in” that the algorithm has found to be not inconsistent with the blurred image.

Ignoring these details of no real-world significance, but concentrating instead on his head as a whole, it can again clearly be seen that JFK’s head rotates forwards from Frame 312 to Frame 313.