Gupta Shubham Kumar, Pal Rishant, Ahmad Azeem, Melandsø Frank, Habib Anowarul
Department of Chemical Engineering, Indian Institute of Technology, Guwahati, India.
Department of Electronics and Electrical Engineering, Indian Institute of Technology, Guwahati, India.
Sci Rep. 2023 Aug 14;13(1):13212. doi: 10.1038/s41598-023-40301-7.
Scanning acoustic microscopy (SAM) is a label-free imaging technique used in biomedical imaging, non-destructive testing, and material research to visualize surface and sub-surface structures. In ultrasonic imaging, noises in images can reduce contrast, edge and texture details, and resolution, negatively impacting post-processing algorithms. To reduce the noises in the scanned image, we have employed a 4D block-matching (BM4D) filter that can be used to denoise acoustic volumetric signals. BM4D filter utilizes the transform domain filtering technique with hard thresholding and Wiener filtering stages. The proposed algorithm produces the most suitable denoised output compared to other conventional filtering methods (Gaussian filter, median filter, and Wiener filter) when applied to noisy images. The output from the BM4D-filtered images was compared to the noise level with different conventional filters. Filtered images were qualitatively analyzed using metrics such as structural similarity index matrix (SSIM) and peak signal-to-noise ratio (PSNR). The combined qualitative and quantitative analysis demonstrates that the BM4D technique is the most suitable method for denoising acoustic imaging from the SAM. The proposed block matching filter opens a new avenue in the field of acoustic or photoacoustic image denoising, particularly in scenarios with poor signal-to-noise ratios.
扫描声学显微镜（SAM）是一种无标记成像技术，用于生物医学成像、无损检测和材料研究，以可视化表面和亚表面结构。在超声成像中，图像中的噪声会降低对比度、边缘和纹理细节以及分辨率，对后处理算法产生负面影响。为了减少扫描图像中的噪声，我们采用了一种4D块匹配（BM4D）滤波器，该滤波器可用于对声学体积信号进行去噪。BM4D滤波器利用具有硬阈值处理和维纳滤波阶段的变换域滤波技术。与其他传统滤波方法（高斯滤波器、中值滤波器和维纳滤波器）相比，该算法在应用于噪声图像时能产生最合适的去噪输出。将BM4D滤波图像的输出与不同传统滤波器的噪声水平进行了比较。使用结构相似性指数矩阵（SSIM）和峰值信噪比（PSNR）等指标对滤波后的图像进行了定性分析。定性和定量分析相结合表明，BM4D技术是SAM声学成像去噪最合适的方法。所提出的块匹配滤波器为声学或光声图像去噪领域开辟了一条新途径，特别是在信噪比低的情况下。
