1. A method of processing an ultrasound spectrum image, comprising the steps of: (a) forming a spectrum image based on ultrasound data; (b) removing a noise from the spectrum image to provide a noise-removed spectrum image; (c) matching the noise-removed spectrum image with one or more spectrum models representing specific spectrum types to check whether or not the noise-removed spectrum image contains an aliasing; (d) detecting, when the noise-removed spectrum image contains the aliasing, a direction and a magnitude of the aliasing based on the matched spectrum model and shifting a baseline of the noise-removed spectrum image based on the detected direction and magnitude of the aliasing to remove the aliasing from the noise-removed spectrum image to provide a noise-removed spectrum image without the aliasing; (e) performing a contour tracing on the noise-removed spectrum image without the aliasing to detect contour points; and (f) performing a peak tracing on the noise-removed spectrum image without the aliasing to detect peaks.