1. An image display apparatus, comprising: a light-emitting unit; a display unit configured to display an image on a screen by modulating light from the light-emitting unit based on image data; a first acquiring unit configured to acquire brightness information on brightness of the image data; an image-processing unit configured to perform image processing on input image data; a second acquiring unit configured to acquire processing information on the image processing; and a control unit configured to control emission brightness of the light-emitting unit based on the brightness information and the processing information, so as to suppress a change in contrast of an image, which is displayed on the screen, caused by the image processing.