The present disclosure relates to an image display apparatus. The image display apparatus includes: a display including an organic light emitting diode panel (OLED panel); and a controller configured to control the display, wherein the controller calculates an Average Picture Level (APL) of an input image, and in response to the calculated APL being greater than or equal to a first reference value in a high-dynamic range (HDR) mode, the controller decreases the APL and perform luminance conversion based on the decreased APL, and in response to the calculated APL being greater than or equal to the first reference value in a normal mode rather than the HDR mode, the controller performs luminance conversion based on the calculated APL. Accordingly, luminance representation may be improved during displaying image.