So last time I told you you could rotate a color. Doesn’t work like you expect?
And a vector could have negative numbers in it! What in the world is Negative blue? And what if I made a vector with a 2 in it? What kind of color is that?
We will address that when talking about High Dynamic Range (HDR) colors, and more interestingly ‘Glowy bits’.
Yeah, well that’s a bit crazy cool subject called ‘color spaces’
Easiest to think about is Hue/Saturation/Value, which is where a rotation makes more sense.
http://beesbuzz.biz/code/hsv_color_transforms.php details using a colorspace called YIQ to do hue rotations that preserve ‘luminosity’
Luminosity is basically a number that details how ‘bright’ a color looks. For example, pure red (1,0,0) is way brighter than pure blue (0,0,1), but they both have the same vector length in RGB colorspace. HSV as well.
An exercise to think about this is to de-saturate an image you paint in only red and blue..
Take every color and take its average. So red == 0.3333 blue == 0.3333.
If instead you ‘weight’ each color with a Luminance value, (0.22, 0.707, 0.071)
you would end up with something that wasn’t a uniform grey and would look more like one would expect.
