Scan conversion is required to display B-mode ultrasonic signals, which are acquired along the scanning radius at varying angles, on standard video monitors. The conventional scan converter involves computation of inverse tangents and square roots to determine, respectively, the scanning angle and depth of a beam. We propose a way to avoid the coordinate transformation and apply 1-D filtering twice to obtain a video pixel. Our system fires the beam line at multiples of the tangent of a specified angle. Because of this special firing, the scan conversion will be done by two filters: a resampling along the beamline to find the pixel (called the radial-grid pixel) which should be the intersection between the beamline and the horizontal line of the image; followed by a re-sampling along the horizontal line to fill in video pixels with the right vertical coordinates. For algorithmic verification, we used computer generated image patterns and generated scan-converted images up to 270 degrees in sector scanning without any artifacts. Moreover, our method has been successfully implemented in DSP software using a single Texas Instrument C6416 chip for real time imaging.
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