Do you mind if I ask you how you know this stuff and where I can get started? I really do want to know more about the chemicals in colours and why, with the history in there too.
We get told what the colour wheel is and never what is in the paints when we are at school. I think we would value the materials more if we had any idea of how we got here.
It's basic organic and maybe advanced inorganic chemistry. The first semester of organic chemistry and probably a higher-level inorganic chemistry course (which is more about where the electrons are than what are the products of reactions). Organic chem is kind of a broad subject but you can start to see why certain patterns have broader absorption spectra and also notice that a lot of azo compounds are pretty toxic.
You can learn organic chemistry from a textbook by just reading and doing every problem in the book. There's also some free online courses and Khan Academy.
I don't think it's easy learn a lot about inorganic chemistry as an autodidact. Teachers are good at emphasizing the important things so that you don't get lost in the weeds.
For reference, you'd be looking at something like MIT's Principles of Inorganic Chemistry I and II (5.03, 5.04) which have organic chemistry I as a prerequisite, which in turn has general chemistry as a prereq.
Then, I imagine, you'd be ready to take on anything in the field of dyes.
We get told what the colour wheel is and never what is in the paints when we are at school. I think we would value the materials more if we had any idea of how we got here.