I was never able to see them until someone told me a tip. If you wear glasses or contact lenses, try looking at it without your corrective lenses. Put your face really close, like 2-3" away.
I'm extremely nearsighted and now see the image quickly and easily with my glasses off. Once I did that, I also can see them with glasses, but it takes much longer for my eyes to focus. I can't explain it, but it works for me.