The equipment radiates and receives ultrasonic sound waves in directions following along a number of scan lines which extend into the object. From the signals obtained are calculated data to provide an image representative of the displacement of specific pixel points along the scan lines. An N-data train eliminator performs a data exchange computer operation, with reference to one pixel train, with which the pixels whose data represents the presence of displacement, occur continuously in N pixels in a specified direction, N being a whole number. Data contained in the pixels forming the pixel train are exchanged for data which are representative of the lack of movement.
