A test apparatus includes: a compensation coefficient calculator configured to calculate a main compensation coefficient for a main gradation and a sub compensation coefficient for a sub gradation based on a detected image signal; a primary predictor configured to determine a representative value of each of a plurality of blocks of a display panel based on the detected image signal, and output a prediction compensation coefficient for the sub gradation based on the main compensation coefficient and the representative value corresponding to each of the plurality of blocks; a secondary predictor configured to determine a flag based on the sub compensation coefficient and the prediction compensation coefficient; and a controller configured to output the main compensation coefficient, the representative value, and the flag stored in a memory as compensation data.