HighContrastText

function HighContrastText(ABackground: TColor): TColor;
var
  R, G, B, Luminance: Single;
begin
  // Convert system color to RGB if needed
  ABackground := ColorToRGB(ABackground);

  // Calculate relative luminance using standard coefficients
  // Using ITU-R BT.709 coefficients
  R := (ABackground and $FF) / 255;
  G := ((ABackground shr 8) and $FF) / 255;
  B := ((ABackground shr 16) and $FF) / 255;
  Luminance := 0.2126 * R + 0.7152 * G + 0.0722 * B;

  // If background is dark, return white; if light, return black
  if Luminance < 0.5 then
    Result := clWhite
  else
    Result := clBlack;
end;