title: What is the equation for luminosity in the Windows Paint program using RGB?
body: <p>As the tite suggests, I'm trying to find an equation for the luminosity of a color in terms of its corresponding Red, Green and Blue components in the Windows program Paint. Ultimately, I'm using the equation in a sort of the thought experiment. If I had a screen with say a million pixels, I can find the percentage of pixels that would have to be red, green and blue to make a desired color with a neutral luminosity value of 120 (purely the color I choose, no black or white in it). However, if I wanted to make the color a bit darker (luminosity less than 120), I would not only need pure red, green and blue in it but also black. I just can't figure out how i would go about finding the percentage of pixels that would have to be black to make the desired color. If I wanted to make brown for example (2 red pixels for every green one and no blue pixels), I would have to make a percentage of the pixels black to darken the orange color  to brown. Some data I have collected:</p>
  
  <p>;Luminosity-Percent Black; 120-0; 70-10; 60-20; 40-50; 0-100;</p>
  
  <p>Sorry for the really confusing post, I just can't figure it out :)</p>