function RgbToGray(RGBColor : TColor) : TColor;
var
Gray : byte;
begin
Gray := Round((0.30 * GetRValue(RGBColor)) +
(0.59 * GetGValue(RGBColor)) +
(0.11 * GetBValue(RGBColor )));
Result := RGB(Gray, Gray, Gray);
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
Shape1.Brush.Color := RGB(255, 64, 64);
Shape2.Brush.Color := RgbToGray(Shape1.Brush.Color);
end;