1. A luminance distortion compensating apparatus comprising: an image data receiving circuit configured to receive grayscale image data from a grayscale image displayed on a display panel and to receive full white image data from a full white image displayed on a display panel; and a luminance distortion compensating circuit configured to compensate for a luminance distortion generated by a display panel inspecting apparatus inspecting the display panel, in the grayscale image data, using the grayscale image data and the full white image data, wherein the display panel is configured to display an image that has been compensated using the luminance distortion compensating circuit.