EE4206/EE5806 Digital Image Porcessing -- HSI colour model
1.Hue is a color attribute that describes a PURE colour, whereas saturation gives a measure of the degree to which a pure colour is DILUTED by white light. Intensity is the gray level. The HSI colour model ,decouples the intensity component from the colour-carrying information (hue and saturation) in a colour image
2. The HSI space is represented by a vertical intensity axis and locus of colour points that lie on planes PERPENDICULAR to this axis.
3. look at the colour cube down its gray-scale axis.
4. The hue of the point is determined by an angle from some reference point. Usually an angle 0 degree from the red axis designates 0 hue, and the hue increases counter-clockwise from there.
5. the saturation (distance from the vertical intensity axis) is the length of th vector from the origin to the point.
6. Note that the origin is defined by the intersection of the colour plane with the vertical intensity axis.