This is posted in this forum thread.
Discussion from other engineer-minded and science-minded people are welcome, too.
Name Undisclosed wrote:Hey Mark,
Wanted to open a line of discussion with you on talking about motion blur and and replicating retinal properties.
One thing I've been researching is afterimages/persistence of vision on the retina. One a 30 fps strobed display, this is really clear. Your 30 fps UFO test visually appears as 2 distinct UFOs on a strobed display (panasonic plasma TV). No motion blur, but definitely persistence of vision.
Given what I'm reading about the phenomenon, where the after image persists for approximately 0.04 seconds, this makes sense. A slower cadence doesn't not give the double image, but then motion is lost, and it becomes stop-go series of images.
Obviously, there is a decay rate on the afterimage, and I do not think it is linear. Most of it is probably lost early, since humans can visually distinguish past even 60 fps (0.017 sec per image). I'm trying to research this in some textbooks right now, so I'll let you know what my findings are.
I think this is an important distinction that we need to take into account, since it means there is a limit to what a strobed display can achieve, and we want to balance quality with reducing motion blur and flicker. Similarly, pursuit tracking cameras, which replicating smooth pursuit of the eye, do not replicate the effect of persistence on strobed displays.
As we increase framerates, even with strobed displays, we'll be seeing 2-4 distinct images (the faster the motion, the further apart and the more distinct they will be, and the faster the refresh, the more images we'll see). Of course, with the decay rates, the impact of these images will be variable.
One thing possibility is to digitally blend previous frames based on a decay rate. I would suggest start with a linear decay rate as an academic experiment, but then use the actual decay rate to replicate as best as possible what the eye will actually see.
I'm also looking at smooth pursuit properties, which require saccades (which is a sample-and-hold effect of the eye motion itself) to catch up to angular velocities > 30 degrees/second.
On a 1080p display occupying 40 degrees of your visual field, that's well within the 1000pixels/second standard you are using. But we should also look into upcoming 4K displays, that will be much closer in achieving pixels that are smaller than acuity limits, where 1 ms of image produces 3 pixels of blur (4K display with 40 degrees of visual field) at smooth pursuit limits (30 degrees/second, or ~3000 pixels/second).