Function TriColorFromKelvin

trinity/Tr2KelvinColor.cpp:98–187

}

Vector3d TriColorFromKelvin( float temperature, float tint, Tr2StandardIlluminant whitePoint )
{
	double xc, yc;
	const double T = temperature;
	const double Y = 1.0;

	if( T < 1000.0f || T > 25000.0f )
	{
		return Vector3d( 0.0, 0.0, 0.0 );
	}


	if( T >= 1000.0f && T <= 4000.0f )
	{
		xc = -0.2661239 * ( 1000000000.0 / ( T * T * T ) ) -
			0.2343580 * ( 1000000.0 / ( T * T ) ) +
			0.8776956 * ( 1000.0 / T ) +
			0.179910;
	}
	else
	{
		xc = -3.0258469 * ( 1000000000.0 / ( T * T * T ) ) +
			2.1070379 * ( 1000000.0 / ( T * T ) ) +
			0.2226347 * ( 1000.0 / T ) +
			0.24039;
	}

	if( T >= 1000.0f && T <= 2222.0f )
	{
		yc = -1.1063814 * ( xc * xc * xc ) -
			1.3481102 * ( xc * xc ) +
			2.1855583 * xc -
			0.20219683;
	}
	else if( T > 2222.0f && T <= 4000.0 )
	{
		yc = -0.9549476 * ( xc * xc * xc ) -
			1.3741859 * ( xc * xc ) +
			2.09137015 * xc -
			0.16748867;
	}
	else
	{
		yc = 3.081758 * ( xc * xc * xc ) -
			5.8733867 * ( xc * xc ) +
			3.75112997 * xc -
			0.37001483;
	}

	// Compute base correlated color temperature
	const double X = ( Y / yc ) * xc;
	const double Z = ( Y / yc ) * ( 1.0 - xc - yc );
	const Vector3d cctXYZ( X, Y, Z );

	// Compute white balance
	const double wbY = 0.54;
	Vector2 wbCoeff = Tr2StandardIlluminantToCCT( whitePoint );
	const double wbX = ( wbY / (double)wbCoeff.y ) * (double)wbCoeff.x;