When I saw this prototype for a game idea (great site, btw.), I immediately thought of the usage as a CAPTCHA. It is very easy for a human to distinguish foreground and background. Would it be equally difficult for a computer to read it? I know that traditional CAPTCHAs can be read by a compute more reliably than by a human (http://www.digitaltrends.com/computing/google-cracks-captcha-with-an-algorithm-thats-99-8-percent-accurate/). I am curious because I know very little about efficient image processing. This is why I ask you: would it be very easy for a computer to read CAPTCHAs that are generated by a moving/still white noise, as you can see in the prototype I linked? Or could you think of a technique that would require little processing costs thus making my idea useless?
I think this would be very easy for a computer to eliminate the moving parts and keep the static parts especially if this is an animated gif. Possibly better would be a standard captcha where all elements slowly move and mutate, e.g. Letters, lines, white noise and distortions. This would be best as a video rather than a gif, purposefully low quality to stimey ocr attempts.
However, all captcha is a beaten problem, as it can be gotten around simply by proxying the captcha through a separate porn site, unknowing users will solve the captchas, which you then immediately use to validate the accounts on the target site, while users are thinking it is giving them access to naked ladies. This is very hard if not impossible to fight.
Edit: you also have to consider how you will allow blind and partially sighted users access to your systems. In some jurisdictions it is a requirement to accommodate those with disabilities so you will need to provide a way around it. Even if you aren't legally obliged to allow access, it is good manners and good business sense to do so. Something to think about...
