The present invention relates to an ultrasound system for providing ultrasound images in a duplex mode. The ultrasound system comprises a transmission/reception unit for alternately transmitting a first ultrasound beam and a second ultrasound beam to a target object. The first and second ultrasound beams are transmitted for first and second time durations, respectively. The ultrasound system further comprises an image processing unit for forming a first diagnostic mode image based on echoes of the first ultrasound beam and a second diagnostic mode image containing a gap corresponding to the first time duration based on echoes of the second ultrasound beam. The image processing unit is further configured to perform gap filling based on edge points of the second diagnostic mode image to form a second diagnostic image with the gap removed.
