Thanks for your thoughts. The issue is user should be able to interact with the system. For example after viewing the flickering image for couple of seconds, user should make a choice and click/touch.
Then combined solution, arduino can be connected to computer and when someone clicks, arduino stops blinking image and notifies program, which does what it needs. Then when program is ready to blink another image, it shows blank screen, notifies arduino to start blinking again and then shows image. Cycle repeats. If you need better responses, you should provide more data about what is required, what you need to measure.