FPGA-Accelerated Hybrid Lossless and Lossy Compression for Next-Generation Portable Optoacoustic Platforms

Optoacoustic (OA) imaging combines optical excitation and ultrasound beamforming to render images of deep tissues with functional contrast and high spatial and temporal resolution; however, its high data rates and large channel count pose significant challenges to developing portable OA systems with limited bandwidth and computational resources. In this context, on-device data compression is required to maximize the information throughput. Traditional lossless compression (LLC) preserves image fidelity but is characterized by non-constant compression ratios that can result in bandwidth saturation. On the other hand, lossy compression (LC) achieves higher and controlled compression at the expense of image quality. This work presents an FPGA-based hybrid compression algorithm that dynamically combines LLC and LC to adapt to bandwidth constraints in real-time, ensuring consistent data transmission while preserving critical image features. Implemented on a Xilinx Kria K26 FPGA, the algorithm can compress 400 MSamples/s, processing multiple analog-to-digital converter channels per compute unit with low FPGA resource utilization (27.1k registers and 35.1 Look-up tables). The hybrid algorithm achieves an average compression ratio of 5.3 ± 0.3 in LLC mode and up to 11 ± 0.1 when the recovery mode activates LC, validated on 6,000 frames of a human OA dataset. Image quality comparisons on human vasculature datasets show that key anatomical details are preserved even during LC. The proposed approach prevents bandwidth saturation without significant hardware overhead, supporting the development of next-generation portable OA imaging systems with efficient and low-cost I/O interfaces.