Ultrasound-based flow measurement relies on the proper knowledge of the angle under which the acoustic waves propagate with respect to the flow direction of the streaming fluid. We present a novel image processing approach for the identification of the wavefronts' orientation by exploiting a modified Hough transform. The spatially discretized sound pressure amplitude of measurement/simulation data is utilized as a weighting function for the Hough transform. It is shown that the angle and

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... n of a wavefront can be estimated with subpixel accuracy, where the size of a pixel depends on the data's spatial resolution. This is achieved by incorporating a least-squares algorithm, fitting a 2D Gaussian function to the Hough parameter plane and thus improving the accuracy of the detected wavefront properties.