I don't see what the problem might be. When you bring your consciousness into normally unconscious states, you unfold your mind, like a deck of cards to see what's there. This is one of the things that are useful in AP because it shows you what's up there in the noggin. When you get images, it's the brain creating them as an automatic mechanism, like the heartbeat or breathing. It has nothing to do with your choice. When you try to 'quiet your mind' it's a different thing, because verbal thoughts are usually caused by the observer observing what's happening and commenting. This is something that can be handled, if not stopped per se, because what you're trying to do is attain some sort of control of your conscious mind. But what causes images is not conscious mind, it's your biological unconscious mind. You really don't want to do that, only brain damage does that, and that is not a positive.
Consider hypnagogics as markers for trance- they tell you your brain has gotten 'almost there', and if there is a problem is your conscious reaction to them. What you want is dispassionate observation- equanimity.