function Colorize(RGB, Luma: Cardinal);
var
 l, r, g, b: Single;
begin
 Result := Luma;
 if Luma = 0 then { it's all black anyway}
  Exit;
 l := Luma / 255;
 r := RGB and $FF * l;
 g := RGB shr 8 and $FF * l;
 b := RGB shr 16 and $FF * l;
 Result := Round(b) shl 16 or Round(g) shl 8 or Round(r);
end;