A method for detecting a region of interest (ROI) is provided, which includes acquiring a plurality of photographed images by photographing a display apparatus sequentially displaying thereon a plurality of different mono-color images, comparing gray levels of the plurality of photographed images and detecting a target region, and detecting a plurality of corner points of the target region, and detecting the region of interest (ROI) corresponding to a display screen of the display apparatus based on the plurality of corner points.