Ultrasonic systems are widely used in imaging applications for non-destructive evaluation, quality assurance and medical diagnosis. These applications require large volumes of data to be processed, stored and/or transmitted in real-time. Therefore it is essential to compress the acquired ultrasonic radio frequency (RF) signal without inadvertently degrading desirable signal features. In this paper, two algorithms for ultrasonic signal compression are analysed based on: sub-band elimination using discrete wavelet transform; and decimation/interpolation using time-shift property of Fourier transform. Both algorithms offer high signal reconstruction quality with a peak signal-to-noise ratio (PSNR) between 36 to 39 dB for minimum 80% compression. The computational loads and signal reconstruction quality are examined in order to determine the best compression method in terms of the choice of DWT kernel, sub-band decomposition architecture and computational efficiency. Furthermore, for compressing a large amount of volumetric information, three-dimensional (3D) compression algorithms are designed by utilising the temporal and spatial correlation properties of the ultrasonic RF signals. The performance analysis indicates that the 3D compression algorithm presented in this paper offers an overall 3D compression ratio of 95% with a minimum PSNR of 27 dB.

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Ultrasonic industrial and medical imaging applications involve acquisition of large amount of volumetric data in real time. Therefore, data storage becomes critical in many current day applications which utilise ultrasound technology. Compressing the acquired data allows possessing minimal storage and also helps to rapidly transmit information to remote locations for expert analysis. The objective of this study is to design computationally efficient architectures for implementing discrete wavelet transform-based ultrasonic three-dimensional (3D) data compression algorithm on a reconfigurable ultrasonic system-on-chip (SoC) hardware platform. In this study, hardware and software architectures of the 3D ultrasonic compression algorithm are realised using Xilinx Zynq all programmable SoC. This study demonstrates that, compressing 33 MB of experimental ultrasonic 3D data into 0.42 MB (98.7% compression) requires only 84 ms for hardware architecture, and 1 min for software architecture, making both designs highly suitable for realtime ultrasonic imaging applications. Furthermore, the 3D compression is implemented by using Open Computing Language (OpenCL) targeted on Nvidia GT 750M graphical processing unit. OpenCL implementation of ultrasonic 3D compression algorithm completes the execution in <1 sec. This approach provides improved computational performance as that of hardware architecture, and comparable flexibility as that of software implementation.

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