Well its very clear :). Anyway if you want to test if the image is authentic or just an illusion, you can try taking zikr from it or talking to it! I can tell you the method:
When the Moon is full and in the east, look for the image Imam Mehdi respectfully and with a clear mind. Then, close your eyes, put your hand on your heart and feel your heartbeats. Then with those heartbeats say Allah, Allah, Allah three times and you will feel the difference.