An image display apparatus includes an image display unit having a light source and a light modulating unit; a histogram generating unit; a function generating unit; a first brightness calculating unit; a second brightness calculating unit; a first difference calculating unit; a first multiplying unit; a first summation calculating unit; a first brightness gradient calculating unit; a second brightness gradient calculating unit; a second difference calculating unit; a second multiplying unit; a second summation calculating unit; a weighted linear sum calculating unit; a determination unit; a control parameter selecting unit; and a control unit.