Summer grass under the light of a sunset might actually turn violet, but color constancy will cause a painter to make it green. That creates color conflict in the painting and makes it feel out of harmony.
The form shadow of a pumpkin in sunlight might actually appear a dark red orange, but color constancy can cause the painter to paint it dark orange which makes the pumpkin's painted image feel flat.
We can train ourselves to read the hues our eyes are seeing when we rid ourselves of remembered perception and ask
ourselves which hue are we seeing.
