The present invention relates to an ultrasound system. A control generates a first control signal for a B-mode scan and a second control signal for a C-mode scan A transmit/receive unit transmits ultrasound signals along a plurality of scan lines set in a target object and form receive signals based on the ultrasound echo signals reflected from the target object. The receive signals include first receive signals corresponding to the scan lines and second receive signals corresponding to a portion of scan lines within the color box. The image processing unit forms a B-mode image and a C-mode image based on the first and second receive signals, and combine the B-mode image with the C-mode image to form a BC-mode image. The control unit computes a time ratio of a first time required to form the B-mode image to a second time required to form the C-mode image, and generates a third control signal for a B-mode scan along scan lines, which are not within the color box, based on the time ratio to form third receive signals. The image processing unit forms a B-mode image based on the third receive signals and the second signals.
