I have read that subjectivity means something which is unique to a person's perspective. An example of something subjective might be color, but is that really something unique to a perspective? If a person is aware of a color isn't the "perspective" the awareness of that color, and isn't the awareness of the color separate from color proper? If that is the case isn't there a sense in which colors are just as external to our being and as objective as primary properties? The attitude of a child is to not distinguish between the secondary and primary properties so that colors are real features of the world but isn't this seeming mistake a product of the fact that awareness is in a sense fundamentally distinct from that which it is aware of? Of course on the other hand it seems hard to imagine colors not existing without a perceiver so I don't know, I'm guessing that philosophers have discussed this issue.
You'll find many of your questions about color discussed helpfully in the SEP entry available at this link .