Doug Kerr
Well-known member
HSV/HSL color models and the "hexcone" and "bi-hexcone" - new tutorial article
In a recent thread here, I discussed the "hexcone" and "bi-hexcone" figures often cited in connection with the HSV and HSL color models, respectively. These are said to "represent" the two color spaces, or perhaps their gamuts, but it is not at all clear what that might mean. For one thing, these geometric figures are not three-dimensional "plots" of the gamuts of the color spaces in their own native coordinate systems, nor in any other recognizable coordinate system (or color space).
While the tapering of the "bi-hexcone" figure (for HSL) at its top and bottom is said to reflect that some property of the color space is available over a range that declines as the luminance either increases to its maximum (at "white") or decreases to "black", we cannot discern just what that property is - and in any case, the vertical axis of the figure cannot represent luminance (the shape of the figure does not comport with that).
I have just posted to my technical information site, The Pumpkin, a new tutorial article, "The HSV and HSL Color Models and the Infamous Hexcones", available here:
http://Doug.Kerr.home.att.net/pumpkin/index.htm#HSV-HSL
This article investigates the mystery surrounding the geometric figures in depth, with extensive illustrations. The "hexcone" metaphor is traced back to the work of Alvy Ray Smith, who developed the HSV color model.
The conclusion of the article is that the hexcone and bi-hexcone figures do not have any real meaning, do not in any way "represent" the two color spaces or their gamuts, and do not help us visualize any of their properties.
This article is published in celebration of my 72nd birthday, today.
In a recent thread here, I discussed the "hexcone" and "bi-hexcone" figures often cited in connection with the HSV and HSL color models, respectively. These are said to "represent" the two color spaces, or perhaps their gamuts, but it is not at all clear what that might mean. For one thing, these geometric figures are not three-dimensional "plots" of the gamuts of the color spaces in their own native coordinate systems, nor in any other recognizable coordinate system (or color space).
While the tapering of the "bi-hexcone" figure (for HSL) at its top and bottom is said to reflect that some property of the color space is available over a range that declines as the luminance either increases to its maximum (at "white") or decreases to "black", we cannot discern just what that property is - and in any case, the vertical axis of the figure cannot represent luminance (the shape of the figure does not comport with that).
I have just posted to my technical information site, The Pumpkin, a new tutorial article, "The HSV and HSL Color Models and the Infamous Hexcones", available here:
http://Doug.Kerr.home.att.net/pumpkin/index.htm#HSV-HSL
This article investigates the mystery surrounding the geometric figures in depth, with extensive illustrations. The "hexcone" metaphor is traced back to the work of Alvy Ray Smith, who developed the HSV color model.
The conclusion of the article is that the hexcone and bi-hexcone figures do not have any real meaning, do not in any way "represent" the two color spaces or their gamuts, and do not help us visualize any of their properties.
This article is published in celebration of my 72nd birthday, today.