just a second thought: if two people are standing beside each other and they interpret the same image from the same screen as different colours, one (or both) of them has damaged vision. it's not "subjective"; your brain is doing it wrong. 2+2=4. a better analogy is perhaps to the error your computer makes when doing arithmetic. it's widespread, and requires error-correcting, but it's not an issue of subjectivity.

there is no subjectivity in vision, or interpreting vision. that is absolute pothead nonsense, and any "doctor" suggesting it to you got their phd from the timothy leary school of dumb hippie nonsense. which is, short hand, referred to as the psychology department in most existing institutions. not science.

there are, however, a lot of undiagnosed eye conditions.