Visual Studio 2010 custom color picker

On the right end, there is a vertical slider, which I think is meant for you to choose the "intensity" of the color, eg darker red or paler red. Is this correct?

The second question, as a layman to colors, I'd thought a dark red and a pale red has the same RGB proportion? But apparently this is not the case. Are darker color and paler 开发者_开发技巧color of the same color actually to non-related colors?

On question 1 yes, in laymans term it increases the intensity. But what really happens is this

double R; double G; double B; double Luminosity = Math.Sqrt(.0241 * (Math.Pow(R, 2)) + 0.691 * (Math.Pow(G, 2)) + 0.068 * (Math.Pow(B, 2)));

Which is a formula for Luminosity based on RGB