Of course praying TO an image is wrong, but using an image (or visual aide, if you will) to prompt deeper contemplation is fine, I think. I really have a hard time staying focused on prayer and meditation (my mind is always wandering----very undisciplined neuro-transmitters!),so using pictures to help me stay focused, or using a rosary to count and say prayers as I meditate on Christ helps me.
And it goes even further than that. Its not merely prayer - its *worship* - and in the most general forms. Spend too much time in the mirror? Spend your energy lusting after Mammon? Investing your "faith" in temporal laws at the expense of God's laws? Idolitry all.