Well, that's very exciting! Perhaps length would be at the objective extreme, but even there we at least sometimes need to make a distinction between physical and perceived length, for example in the T illusion. I see the gap between spectral distribution and colour as being at the other extreme, in that there are two gaps of subjectivity involved. With just three cone cell types we can't know the spectral distribution of a light, only some limited qualities of it (dominant wavelength and purity as defined by an opponent visual system), so many different spectral distributions look identical to us. And then these limited qualities that we do detect are tagged for us with entirely subjective experiences whose relationships have no basis in the linear spectrum. In between you have perceptions that correlate more directly (if non-linearly) with the physical stimulus, such as sound and vibration rate, or warmth and molecular motion.