A method for optical calibration of a plurality of displays is provided. At a manufacturing stage, a plurality of one-time programmable (OTP) values for each display is created, each OTP value including a value of manufacture gamma voltage corresponding to a manufacture luminance and color value. The OTP values are stored in non-volatile memory of the respective display. At an assembly stage, each display is connected to a respective power management integrated circuit (PMIC); assembly test voltages are applied corresponding to the manufacture gamma voltage of each stored OTP value. Differences between assembly luminance and color values of each display and an expected value as a result of applying each assembly test voltage are measured. For each display, one value of manufacture gamma voltage of a respective OTP value is selected that corresponds to a minimal difference between the assembly luminance and color values and the expected value.