An image display apparatus including multiple pixel elements which are configured to display an image, a first power source which is configured to apply a voltage to the multiple pixel elements, a counter which is configured to output counter signals, a ramp generator which is configured to receive the counter signals and output ramp signals according to the counter signals, a second power source which is configured to apply a voltage to the multiple pixel elements according to the ramp signals, an amplifier which is configured to output a trigger signal in case that a first pixel element in the multiple pixel elements outputs an electric current, a data driver which is configured to output a counter value according to the counter signal and the trigger signal, and a buffer which is configured to store the counter value.