Comment by emerged

There's a wall at my parents house which to me always looked green. I referred to it as green and my sister and mother seemed to get downright angry, insisting it was blue. I don't really care either way, it just looks green to me. I can't stop seeing it as green.

If you were to analyze the wavelengths of light the wall, or your notebook, consist of, you'll find a certain amount of blue and a certain amount of green. The thresholds which are detected by our eyes, and the thresholds relative to that where we subjectively determine the dominant color, has high variance.

But people take their subjective perception dead serious, since their perspective is the only one which matters.