Understanding contrast improvements from capon beamforming

This paper investigates the contrast improvements seen when using adaptive (Capon) beamforming to create ultrasound images. Ultrasound images of cysts have been simulated using linear array imaging in Field II. The contrast of the cyst compared to the speckle surrounding it has been investigated, especially the improved edges produced by the Capon beamformer. We show that it is the improved edges that cause the contrast improvements. The resulting beampattern from the Capon beamformer has been compared to the beampattern from the conventional delay and sum (DAS) beamformer with different apodizations to show how the improved edges are generated. Finally, a bright inclusion was added to the simulation to demonstrate how the visual contrast changes when the image contains multiple intensity plateaus.