Avoid visually ambiguous characters in URL

I appreciate that you need to have case sensitive URLs, else URLs would already be much longer, but when generating a URL for an image, can you add a filter to reject URLs that have visually ambiguous characters? (No capital 'I's or lowercase 'L', No capital 'O's or number 0, etc) I know most in most cases users link, but hand copying happens often enough that it becomes a major annoyance.