An image output apparatus includes: a display device having a light modulation section which is divided into a plurality of channels; a level adjusting unit that is provided to each of the channels, adjusts a level of input signal, and outputs adjusted output signal to corresponding channel; a signal switching unit that switches between a video input signal and a first reference signal as the input signal of the level adjusting unit, for a predetermined period; an adjustment amount correcting unit that compares an output signal from each of the level adjusting units with a second reference signal for the predetermined period and corrects the adjustment amounts of the corresponding level adjusting units on the basis of the comparison results; and a connection state switching unit that outputs a control instruction to the display device to change a state of the channels to an open state for the predetermined period.