Displaying an image with unevenness correction by measuring Vgs-Id characteristics of the transistors in a subset of pixels; approximating each characteristic using an equation of the form Id=(a(Vgs−b))c; calculating a value c′ using the approximations; measuring the characteristics of the remaining pixels; approximating each of those characteristics by an equation of the same form, using c′ as the power for all of the approximations, calculating corrected image signals for each pixel using the respective approximations of the corresponding pixels of the display device to correct for unevenness; and applying the corrected image signals to the corresponding pixels of the display device to display a corresponding image with unevenness correction.