I have had a project in mind for a while that I have never gotten around to, that I do not have the technical knowledge for, and that I think would probably be out of my budget. I’ll write it up here anyways.
One difference between the way analog and digital cameras capture a photo is that analog cameras expose the entire roll of film at once while digital sensors expose a single column of pixels at a time. So (as I understand it) if you have a shutter speed of 1/10th of a second, and a camera that is 1000×1000 (1 megapixel), then each successive column of pixels is exposed for 1/10,000th of a second as the camera takes its photo. This 1/10,000th of a second is called the “rolling shutter speed.”
I discovered this interesting fact through an industrial security/research project called LiShield. In a fascinating paper, the authors Shilin Zhu, Chi Zhang, and Xinyu Zhang propose to exploit the rolling shutter speed feature as a way to enhance the privacy of certain spaces by modulating an LED light faster than the shutter speed but slower than the rolling shutter speed to create bars of high and low light exposure in any image taken with a smartphone. For example, if you have a light that cycles on/off once every 1/100th of a second, the resulting image of a 1/10th of a second exposure will be 10 bright lines and 10 dark lines. Here’s an example from the paper: