1. An image display method performed by an electronic device, the image display method comprising: acquiring block importance values of a plurality of blocks corresponding to an image; determining a reference region including at least one block among the plurality of blocks based on the acquired block importance values and a predetermined reference; enlarging a size of the determined reference region based on the block importance values to determine a main region having a predetermined shape and a predetermined size in the enlarged reference region; and displaying a portion of the image corresponding to the main region.