A method of evaluating and optimizing the density of the ink deposited on the substrate during printing. The ink strength—or print contrast—is determined to take into account the solid ink density, the density of the ink in shadow areas of the image, and the dot gain. Print contrast is calculated by measuring the ink density of a solid area and the ink density in a 75% tint. The print contrast is calculated according to the formula
where Ds is the solid area density, and Dt is the tint density.