title: How to convert from RGB values to color temperature?
body: <p>How does one take a color expressed in an RGB value (say, three coordinates from 0-255) and produce from it a <a href="https://en.wikipedia.org/wiki/Color_temperature" rel="noreferrer">color temperature</a> in kelvin (or mireds)?</p>
  
  <p>I see <a href="https://stackoverflow.com/questions/13975917/calculate-colour-temperature-in-k#13982347">this question</a> which looks pretty close.  However, the question mentions x and y, <a href="https://stackoverflow.com/a/23030669/34935">an answer</a> mentions R1 and S1, which I think are CIE XYZ color space coordinates.  I'm not quite sure how to get to those either.  Someone else links to a paper.  Someone else <a href="https://stackoverflow.com/a/14079177/34935">says</a> RGB values are meaningless without "stating a color space" (I thought my monitor decided to display something simply from RGB values?).</p>
  
  <p>Can someone just lay out the whole thing without pointing to other places and assuming I know what all the color terminology is?</p>