A method of resolution enhancement is presented for the case of sector‐scan ultrasonic imaging. In this method, a homomorphic transform, in which image reconstruction is carried out on the polar coordinates through the space−variant selection of the received data depending on each reconstruction point, is used so that an image convolved with a space‐invariant 2‐D point‐spread function is obtained. Then, the conventional deconvolution process is applied to get an image with uniformly improved resolution.