For an ultrasound image acquired by an ultrasound detection system, background data with small noises are first filtered. Next, a binary image is generated by performing image binarization on the noise-reduced ultrasound image based on a first threshold value, wherein the binary image contains information associated with the body of high-echo foreground images in the ultrasound image. An output image is generated by performing foreground expansion on the binary image based on the pixel value of the ultrasound image and a second threshold value smaller than the first threshold value, wherein the output image contains information associated with not only the body but also the outline of high-echo foreground images in the ultrasound image. An improved ultrasound image is generated by performing a post-processing on the ultrasound image according to information of foreground and non-foreground region in the output image.