A method of adjusting luminance of a backlight unit included in a liquid crystal display device that performs inversion driving is provided. The method derives a positive polarity histogram and a negative polarity histogram of an image frame based on image frame data, corresponding to the image frame, and a data polarity pattern for implementing the image frame, derives a luminance compensation value according to data polarity dominance of the image frame by analyzing the positive polarity histogram and the negative polarity histogram, and applies the luminance compensation value to the luminance of the backlight unit during a portion of a time period of the image frame.