XYZ 轉色溫的方式

function XYZToColorTemperature(X, Y, Z: Double): Double;
var
  n, u, v, duv: Double;
begin
  // Normalize XYZ values
  n := X + Y + Z;
  if (n = 0) then
    Exit(0);
  X := X / n;
  Y := Y / n;
  Z := Z / n;

  // Calculate u and v values
  u := (4 * X) / (-2 * X + 12 * Y + 3);
  v := (9 * Y) / (-2 * X + 12 * Y + 3);

  // Calculate duv (distance from Planckian locus)
  duv := 0;
  if (u - 0.20917 * v) > 0.46228 then
    duv := (u - 0.20917 * v - 0.46228) / 0.02
  else if ((0.08067 * v - u) > 0.17697) then
    duv := (0.08067 * v - u - 0.17697) / 0.02;

  // Calculate color temperature
  Result := (1.0 / ((-4.607 * duv + 2.9672) * 1e-3) + 1.0 / 500) * 1e3;
end;