I did something similar by piping ffmpeg into a numpy array, with each frame updating the average RGB value of each pixel in the array.
Here's a three-second clip from 'Logan' of a scene where Hugh Jackman's character is leaping through the air from right to left: http://i.imgur.com/EIp56LX.jpg
I like the results better for short sequences, but here's the entirety of 'Logan' (not sure what's causing the dark line down the middle): http://i.imgur.com/3QW6zPj.jpg
Would you mind sharing the code? I find the second example oddly satisfying to look at and would like to experiment with other movies at different resolutions.
You'll need to experiment to find the right value for the variable 'alpha' in the script. This controls each frame's opacity: too high and it will be overexposed, too low and it will be dark. It's roughly in the range 5/n to 40/n where n is the number of frames in the video, but depends on the film's overall moodiness too.
If you're going to run it on a feature film length video, I suggest making a low-resolution version (e.g. 144p) and fine-tuning alpha on that, since it will be significantly less frustrating.
I wonder how a moving average of a movie would look? I think the trick would be in choosing the right length for the moving average window, so that the viewer could still see the "chapter" transitions.
Using analog techniques there is a famous set of photographs of films playing in movie theaters by Japanese artist Hiroshi Sugimoto. In this work a long duration time-lapse photo of the film renders the screen glowing white with a pale outline of the theatre around it. https://www.sugimotohiroshi.com/new-page-7
Cool! I tried something similar using Go + ffmpeg. Eventually wanted to find a way to select the most "continuous" pixel from all available data and spider out, but never got that far. Instead I played around with gifs and space.
you can also do some fun stuff with image averaging in ImageJ. here is a python script for ImageJ I wrote a while back that takes the standard deviation of several frames at a time and averages them onto a background
(https://pastebin.com/09wPkwhN nb: I am a terrible programmer and this was when I was just starting to learn)
that produced this:
http://imgur.com/a/eaLEO
At the beginning of the article, there is a set of a 2 rows x 3 column set of images by Jason Schulman. The last imahlge on the first row, looks kind of like a blurry Albert Einstein.
Here's a three-second clip from 'Logan' of a scene where Hugh Jackman's character is leaping through the air from right to left: http://i.imgur.com/EIp56LX.jpg
I like the results better for short sequences, but here's the entirety of 'Logan' (not sure what's causing the dark line down the middle): http://i.imgur.com/3QW6zPj.jpg