RGB2XYZFunctor< T > Class Template Reference

Convert linear (raw) RGB into standardized tri-stimulus XYZ. More...

#include <vigra/colorconversions.hxx>

Public Types
typedef TinyVector< T, 3 >	argument_type

typedef NumericTraits< T > ::RealPromote	component_type

typedef TinyVector < component_type, 3 >	result_type

typedef TinyVector < component_type, 3 >	value_type

Public Member Functions
result_type	operator() (argument_type const &rgb) const

	RGB2XYZFunctor ()

	RGB2XYZFunctor (component_type max)

Detailed Description

template<class T>
class vigra::RGB2XYZFunctor< T >

Convert linear (raw) RGB into standardized tri-stimulus XYZ.

#include <vigra/colorconversions.hxx>
Namespace: vigra

According to ITU-R Recommendation BT.709, the functor realizes the transformation

$\begin{array}{rcl} X & = & 0.412453\enspace R / R_{max} + 0.357580\enspace G / G_{max} + 0.180423\enspace B / B_{max}\\ Y & = & 0.212671\enspace R / R_{max} + 0.715160\enspace G / G_{max} + 0.072169\enspace B / B_{max} \\ Z & = & 0.019334\enspace R / R_{max} + 0.119193\enspace G / G_{max} + 0.950227\enspace B / B_{max} \end{array}$

By default, $R_{max} = G_{max} = B_{max} = 255$ . This default can be overridden in the constructor. X, Y, and Z are always positive and reach their maximum for white. The white point is obtained by transforming RGB(255, 255, 255). It corresponds to the D65 illuminant. Y represents the luminance ("brightness") of the color. The above transformation is officially defined in connection with the sRGB color space (i.e. when the RGB values are obtained by inverse gamma correction of sRGB), other color spaces use slightly different numbers or another standard illuminant (which gives raise to significantly different numbers).