arXiv:2505.08256cs.LG2025-05

通过分块聚类优化医学图像压缩,更好保留病灶细节。

Clustering-Based Low-Rank Matrix Approximation for Medical Image Compression

  • 将图像分块聚类后局部做奇异值分解,自适应捕捉结构差异。
  • 在四类医学影像上均优于全局分解,尤其提升病灶区保真度。
  • 适合需要高保真压缩的临床场景,如远程诊疗与存储优化。

医学图像具有高分辨率和局部结构变化显著的特点,高效压缩需在保持诊断准确性的同时减少冗余。传统低秩矩阵近似(LoRMA)虽能捕捉全局相关性,但难以适应不同区域的局部结构差异。为此,本文提出一种自适应LoRMA方法:将医学图像划分为重叠块,利用k-means聚类将结构相似的块分组,并在每组内进行奇异值分解(SVD)。推导了考虑块重叠的总体压缩因子,并分析了块大小对压缩效率与计算成本的影响。该方法适用于高局部变异性数据,以医学影像为重点。在MRI、超声、CT扫描和胸部X光四类模态上评估并对比全局SVD。结果表明,自适应LoRMA有效保留了结构完整性、边缘细节和诊断相关性,以PSNR、SSIM、MSE、IoU和EPI为指标均优于全局SVD,显著降低块效应与残差误差,尤其在病理区域表现更优,同时优先保护临床关键区域,允许非关键区更激进压缩,提升存储效率。尽管处理时间更高,但其诊断保真度使其在高压缩应用中具备合理性。

原文摘要 · Abstract (English)

Medical images are inherently high-resolution and contain locally varying structures crucial for diagnosis. Efficient compression must preserve diagnostic fidelity while minimizing redundancy. Low-rank matrix approximation (LoRMA) techniques have shown strong potential for image compression by capturing global correlations; however, they often fail to adapt to local structural variations across regions of interest. To address this, we introduce an adaptive LoRMA, which partitions a medical image into overlapping patches, groups structurally similar patches into clusters using k-means, and performs SVD within each cluster. We derive the overall compression factor accounting for patch overlap and analyze how patch size influences compression efficiency and computational cost. While applicable to any data with high local variation, we focus on medical imaging due to its pronounced local variability. We evaluate and compare our adaptive LoRMA against global SVD across four imaging modalities: MRI, ultrasound, CT scan, and chest X-ray. Results demonstrate that adaptive LoRMA effectively preserves structural integrity, edge details, and diagnostic relevance, measured by PSNR, SSIM, MSE, IoU, and EPI. Adaptive LoRMA minimizes block artifacts and residual errors, particularly in pathological regions, consistently outperforming global SVD in PSNR, SSIM, IoU, EPI, and achieving lower MSE. It prioritizes clinically salient regions while allowing aggressive compression in non-critical regions, optimizing storage efficiency. Although adaptive LoRMA requires higher processing time, its diagnostic fidelity justifies the overhead for high-compression applications.

医学图像压缩算法低秩近似

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