CIELUV Namespace Reference

CIE stands for the International Commission on Illumination, which has defined a color space known as LUV. More...

Functions
template<class T>
double	X_tristim (T r, T g, T b)
	calculate the x tristimulous value from raw rgb.
template<class T>
double	Y_tristim (T r, T g, T b)
	calculate the y tristimulous value from raw rgb.
template<class T>
double	Z_tristim (T r, T g, T b)
	calculate the x tristimulous value from raw rgb.
template<class T>
double	gray (T v)
	calculate luminance L from raw mono, v is val 0-255
template<class T>
double	u_coord (T X, T Y, T Z)
	calculate u chromaticity coordinate (0-1) from tristimulous values
template<class T>
double	v_coord (T X, T Y, T Z)
	calculate v chromaticity coordinate (0-1) from tristimulous values
template<class T, class Q>
void	uv_coord (T X, T Y, T Z, Q &u, Q &v)
	calculate uv chromaticity coordinate (0-1) from tristimulous values
template<class T, class Q>
void	RGB2LUV (T r, T g, T b, Q &L, Q &U, Q &V)
	calculate LUV from raw rgb
template<class T>
double	chroma (T U, T V)
	calculate chroma from LUV
template<class T>
double	hue (T U, T V)
	calculate hue from LUV
template<class T, class Q>
void	LUV2XYZ (T L, T U, T V, Q &X, Q &Y, Q &Z)
	calculate tristimulous values from LUV
template<class T, class Q>
void	LUV2RGB (T L, T U, T V, Q &r, Q &g, Q &b)
	calculate raw rgb from LUV

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Detailed Description

CIE stands for the International Commission on Illumination, which has defined a color space known as LUV.

Anyone who has worked with color values has learned that a change in brightness from 18 to 20 is far more significant than a change from 218 to 220. LUV is a color encoding with uniformity in the perceptibility of color differences that minimizes this problem. Dark differences are emphasized and light color differences are de-emphasized.

A major advantage of the CIELUV space is that it is easy to translate from RGB to LUV and back again. Some of the color spaces in use today do not have that property. The three colors in LUV are Luminance, U (red vs green), and V(blue vs yellow).

PiXFrame has color layers for each of the LUV. In addition, Chroma, Hue, Red, Green, and Blue layes are defined, since they are sometimes useful. Chroma and Hue are derived from the LUV values. Chroma is similar to contrast in other color spaces.

The equations in this version of CIELUV differ from normal in that the values range from 0 to 255 instead of 0 to 99. The tristimulous values remain the tradional 0 to 99. The chromaticity coordinates are 0 to 1.