one of the things I think about as an engineer is that in order for something like this to work,  you should probably start with manuals adjustments to processing the the out-of-focus blur first. after you have finished with this, you can do the motion blur.  I would have to really think hard about it to see if there is an algorithm such as a kernel or something to convert an image into a path. one problem is you are stuck with the image boundaries. if they weren't there, things would be so much easier (but it would also take infinitely long to process).  the image boundaries MIGHT skew the kernel, depending on how you handle the boundaries (for example, usually you just assume those values are black or 0's, or you may choose a 50% gray, whatever fits best with the kernel you are working with).

adobe may be on to something there, but they only had half of the equation with the idea.

I used to tinker with image processing many yarns ago back for fun in BASICA/GWBASIC.

if you have the kernel

[-2 0 2]

[-2 0 2]

[-2 0 2]

which amplifies vertical lines, you would want to handle the boundaries by processing them as 0's.

NOTE TO ADOBE: it might start getting into Machine Vision technology when you start doing the path recognition. or AI.

if you can get the imge into a path kernel, it's essentially a bitmap of a path.  you can trace that path using akima spline curves. (will lose 1-2 samples off each end), but the tracing program might just exist out there somewhere.  just google "bitmap to akima spline curve".  and akima spline curve has all the

points along its path, unlike a bezier. I like akima spline curves, I have been trying to get ps engineers to use them for a while for good reason. this is one of them.

there are also cubic splines as an alternative. 

chances are that the curve will have rounded corners due to the weight of the camera.

now that you have the path,it's simply a matter of taking samples along the curve wherever you want. (usually in an array which you can linearly inerpolate across the points in the array for simplicity if you want)