There are many conflicting definitions of the Hue, Saturation and Brightness colour space. In the following documents, we attempt to clear up some of the confusion related to this subject:
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For those of you wondering what the colour gamuts of the proposed spaces look like, the following animations are available (in AVI format). They present a slice through the achromatic axis of the spaces, which rotates through 360°. The achromatic axis is in the middle of the image, and the hue values (in degrees) to the left and right of it are indicated.
L1 norm space: Brightness is the mean of R, G and B, L1 chroma and (non-trigonometric) hue are used.
View
max-min semi-norm space: Brightness is the mean of R, G and B, saturation is the max-min semi-norm and hue is the exact trigonometric version.
View
max-min semi-norm space: The luminance weightings are used for brightness, while the other two coordinates are the same used in the previous animation.
View
Two
Matlab functions which perform the forward and backward conversions between the RGB space and the suggested 3D polar coordinate IHLS (Improved Hue, Luminance and Saturation) colour space are here:
hsy_rgb.zip (Thanks to Thomas Knudsen for the code optimisations).
A
Python version of the above functions, written by Alexander Schindler:
hsy.zip.