Hue and since when?

Discussion in 'Photographic Discussions' started by gravity0, May 5, 2009.

  1. gravity0

    gravity0 TPF Noob!

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    Ok, I was reading another thread about RAW and came across this word so I clicked the link to find out more. I came across Tan (blah, blah) :scratch: Since when is hue or RBG a cirlcle? Who came up with this and what was the reason? I'm curious now, I don't remember going over this in Physics 3, I may have slept through that class. I'm going to have to open that book up again.
     
  2. Garbz

    Garbz No longer a newbie, moving up!

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    Hue or RGB a circle? You are confusing your colour models. The RGB colour model forms a cube like so, and is addressed much the same as standard 3d co-ordinates:
    [​IMG]

    The HSL colour space however forms a cone where S is the radius, L is the height, and H is the radius which is addressed in polar co-ordinates.
    [​IMG]

    The idea is that Hue flows freely in a circle since it only determines the primary shade of the colour and not it's brightness or saturation. This means that when in a rainbow when you get to the end you should be able to simply start again. i.e. Hue of 0 degrees = hue of 360 degrees.

    Who came up with it, no one knows. Alvy Ray Smith formalised it mathematically, though, and there's no good reason why to use Hue Saturation and Lightness, over Red Green Blue, other than it's a different way to visualise the working colours you can use. As for photography, well they create a nice way to transform an image.
     

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