An electronic device includes at least one processor, and at least one memory storing instructions executable by the at least one processor and operatively connected to the at least one processor, where the at least one processor is configured to acquire voice data to be synthesized with at least one first image, generate a plurality of mouth shape candidates by using the voice data, select a mouth shape candidate among the plurality of mouth shape candidates, generate at least one second image based on the selected mouth shape candidate and at least a portion of each of the at least one first image, and generate at least one third image by applying at least one super-resolution model to the at least one second image.