0031454: Visualization - perceptually uniform color scale

[occt.git] / src / Quantity / Quantity_TypeOfColor.hxx

diff --git a/src/Quantity/Quantity_TypeOfColor.hxx b/src/Quantity/Quantity_TypeOfColor.hxx
index ba70a48..affa420 100644 (file)
--- a/src/Quantity/Quantity_TypeOfColor.hxx
+++ b/src/Quantity/Quantity_TypeOfColor.hxx
@@ -20,13 +20,50 @@
 //! Identifies color definition systems.
 enum Quantity_TypeOfColor
 {
-  Quantity_TOC_RGB,  //!< normalized linear RGB (red, green, blue) values within range [0..1] for each component
-  Quantity_TOC_sRGB, //!< normalized non-linear gamma-shifted RGB (red, green, blue) values within range [0..1] for each component
-  Quantity_TOC_HLS,  //!< hue + light + saturation components, where:
-                     //!  - First component is the Hue (H) angle in degrees within range [0.0; 360.0], 0.0 being Red;
-                     //!    value -1.0 is a special value reserved for grayscale color (S should be 0.0).
-                     //!  - Second component is the Lightness (L) within range [0.0; 1.0]
-                     //!  - Third component is the Saturation (S) within range [0.0; 1.0]
+  //! Normalized linear RGB (red, green, blue) values within range [0..1] for each component
+  Quantity_TOC_RGB,
+
+  //! Normalized non-linear gamma-shifted RGB (red, green, blue) values within range [0..1] for each component
+  Quantity_TOC_sRGB,
+
+  //! Hue + light + saturation components, where:
+  //! - First component is the Hue (H) angle in degrees within range [0.0; 360.0], 0.0 being Red;
+  //!   value -1.0 is a special value reserved for grayscale color (S should be 0.0).
+  //! - Second component is the Lightness (L) within range [0.0; 1.0]
+  //! - Third component is the Saturation (S) within range [0.0; 1.0]
+  Quantity_TOC_HLS,
+
+  //! CIE L*a*b* color space, constructed to be perceptually uniform for human eye.
+  //! The values are assumed to be with respect to D65 2&deg; white point. 
+  //!
+  //! The color is defined by:
+  //! - L: lightness in range [0, 100] (from black to white)
+  //! - a: green-to-red axis, approximately in range [-90, 100]
+  //! - b: blue-to-yellow axis, approximately in range [-110, 95]
+  //!
+  //! Note that not all combinations of L, a, and b values represent visible
+  //! colors, and RGB cube takes only part of visible color space.
+  //!
+  //! When Lab color is converted to RGB, a and b components may be reduced
+  //! (with the same proportion) to fit the result into the RGB range.
+  Quantity_TOC_CIELab,
+
+  //! CIE L*c*h* color space, same as L*a*b* in cylindrical coordinates:
+  //! - L: lightness in range [0, 100] (from black to white)
+  //! - c: chroma, approximately in range [0, 135], 0 corresponds to greyscale
+  //! - h: hue angle, in range [0., 360.]
+  //!
+  //! The hue values of standard colors are approximately:
+  //! - red at 40, 
+  //! - yellow at 103,
+  //! - green at 136,
+  //! - cyan at 196,
+  //! - blue at 306,
+  //! - magenta at 328.
+  //!
+  //! When Lch color is converted to RGB, chroma component may be reduced
+  //! to fit the color into the RGB range.
+  Quantity_TOC_CIELch
 };
 
 #endif // _Quantity_TypeOfColor_HeaderFile