Embodiments for correcting a dropout in a strain image in an ultrasound system are disclosed. In one embodiment, a processing unit sets a first window on each of pre-compression ultrasound frame data and post-compression second ultrasound frame data, move the first window in a predetermined direction and compute a correlation between the pre-compression ultrasound frame data and the post-compression ultrasound frame data within the first window to obtain a displacement corresponding to a value of each pixel of target ultrasound frame data. The processing unit sets one of pixels of the target ultrasound frame data as a reference pixel, sets a second window to encompass predetermined numbers of pixels positioned around the reference pixel, checks whether a displacement computation error corresponding to a dropout occur based on the pixel values within the second window and resets, when the dropout occurs, the value of the reference pixel.