No, what your dealing with is various saturation levels of blue. Brightness level of blue is determined by the "b" value.
I'm not the one who is confused . No red in a color would be only when r = 0. For a color be be a red, r would need to be the highest value, for a color to be reddish or have a red cast, r would need to be at least the second highest value, but for the color to have no red, r would have to be 0. That's what no means - none, zip, nada, zilch
In that case, this is a case about terminology confusion, and I'm at blame.
Yes, I mean that the sky doesn't have a red cast.
Let me try to be a bit more precise about what I meant to say (and keep in mind that I'm not Bruce Fraser or Andrew Rodney ).
The original claim was that "a blue sky has more red than you might think, since it is not that saturated"
, and bjanes then proceeds to use an RGB representation of the sky as a proof.
This is where I think that he misunderstands the RGB colour model, and forgets that it's just a simulation. That there is a "red" value in RGB doesn't mean that the sky "has red" in it.
Keep in mind that RGB (regardless of colour space) is used to simulate a part of the visible spectrum by using a three-colour composite. Yes, the representation
in RGB is using red to simulate
the visible spectrum, but you could just as well say that a sky with 128,128,255 "has yellow" (since 128,128,0 is a dark yellow), or that a bright blue sky "has cyan", "has turquoise", "has mauve", "has maroon", "has green", "has violet", "has ultraviolet", "has x-ray", ...
Since it's possible to use an N-colour composite instead of the 3-colour composite RGB, and still be able to simulate the visible spectrum, it's possible to have models where red isn't one of the components. CIA L*a*b* is one model that doesn't use red as a component (its three axes are lightness from black to white, green to magenta and blue to yellow). Or you could've used a two-colour composite of orange and blue.
Would you still claim that -- in that two-colour composite -- the sky "has red"?
Going back to RGB, the value set of 128,128,255 isn't a simulation of a colour with red in it. It's a simulation of a clear blue.