Embodiments of providing an enlarged image, without degradation of image quality are disclosed. The ultrasound system includes an ultrasound data acquisition unit, a user input unit and a processor. The ultrasound data acquisition unit is configured to acquire ultrasound data representative of a target object. The user input unit is configured to receive user input information. The processor is configured to extract ultrasound data corresponding to the user input information from the acquired ultrasound data, perform a decimation process on the extracted ultrasound data based on a zoom ratio corresponding to the user input information and form an enlarged image corresponding to the zoom ratio by using the decimated ultrasound data.
