Embodiments for forming an elastic image in an ultrasound system are disclosed. In one embodiment, a processing unit is configured to control an ultrasound data acquisition unit to perform the transmit/receive operation in a first state where compression is not applied to the target object to thereby obtain a first ultrasound frame data set, and to perform the transmit/receive operation in a second state where compression is applied to the target object to thereby obtain a second ultrasound frame data set. The processing unit is further configured to compute a first strain between the first and second ultrasound frame data sets, perform globally uniform stretching upon the second ultrasound frame data set based on the first strain, and compute a second strain between the first ultrasound frame data set and the stretched second ultrasound frame data set and form an elastic image based on the second strain.
