An apparatus for driving a display device includes a timing controller and a data driver. The timing controller encodes first gray scale data of a present frame, decodes encoded second gray scale data of a previous frame, compares the first gray scale data with the second gray scale data, and generates compensated gray scale data based on a result of comparing the first gray scale data with the second gray scale data. The data driver generates data signal based on the compensated gray scale data to provide the data lines with the data signal. The gray scale data are encoded so that the toggle number between adjacent data pins into which the gray scale data are output may be reduce. The encoded gray scale data are stored in a memory. Thus, the power consumption is reduced, and the EMI may be reduced.