In this experimental study, we conducted measurements using a 128-element ultrasonic array system. Ultrasonic images generated by the conventional migration method were compared with the Envelope method, a promising high-resolution imaging technique. To determine the image quality of an ultrasonic measurement system that uses fewer elements, we selected 64, 32, 16 and 8 elements from the total 128 elements used in our imaging process. The results show that in homogeneous environments the Envelope method can produce clearer images than those produced by the conventional method even when using a small number of elements, suggesting that the introduction of the Envelope method could be an effective way of reducing the number of elements employed in array systems, while maintaining high image quality. © 2011 The Acoustical Society of Japan.