image vector correlates with the relative angular velocity for the transducer at the image vector a high average frequency value indicates a relatively high angular velocity for the transducer at the image vector and a low average frequency value indicates a relatively low angular velocity for the transducer at the image vector for a transducer rotating at a constant angular velocity the average frequency values for the image vectors is noted to be fairly constant in step 250 the integral of the average frequency values for all the image vectors is computed with the integral normalized to a value of 2 u03c0 radians which is the angle of one revolution of the transducer in step 260 an estimate of the actual angle for each image vector is computed using the running value of the normalized integral at the image vector this estimated angle for each image vector takes into account the fact that image vectors are not taken at uniformly spaced angles in step 270 each image vector is remapped to its respective estimated angle to produce a nurd corrected image in other words nurd is reduced or eliminated by deriving an estimated angle for each image vector and using that estimated angle instead of the inaccurately assumed uniformly spaced angle the value of the width w and u03c7 used to compute weight of the window in step 220 may be optimized through normal experimentation for example a phantom e g made of rubber having a known cross sectional profile may be imaged using a rotating transducer the.