Image recognition is an essential theme to be studied for image reproduction with better satisfaction by observers. Study of visual illusion is one of approaches for clarifying recognition process in our eyes and brain. That is why we have chosen the moon illusion as a study theme of imaging technology. A full moon just above the horizon is often recognized as much larger than an elevated moon. The reason remains an open question in spite of having been studied since the ancient Greece period. Here we show a new explanation for this illusion.We suggested a new explanation that miss-understanding of distance to the horizon moon causes inappropriate compensation of size recognition of the moon.The validity of our new hypothesis was checked by our simulated observation of a moon. Exaggeration of a moon image was observed by our simulation to look at a moon through a deep corridor as a projected image on a screen. The deeper was the corridor, the larger moon was observed. The observed results were as our hypothesis had predicted; our hypothesis was agreed by our experimental results.