Laser & Optoelectronics Progress, Volume. 62, Issue 14, 1411002(2025)

Optimization Method for Underwater Scattering Imaging Based on Off-Axis Digital Holography

Quan Liu1, Ying Jin2,3,4、*, Quanying Wu1、**, Weixuan Yi2,3,4, Haofan Wang2,3,4, and Guohai Situ2,3,4
Author Affiliations
  • 1College of Physical Science and Technology, Suzhou University of Science and Technology, Suzhou 215009, Jiangsu , China
  • 2Aerospace Laser Technology and System Department, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
  • 3Wangzhijiang Innovation Center for Laser, Shanghai 201800, China
  • 4Key Laboratory of Space Laser Communication and Detection Technology, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
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    Figures & Tables(21)
    Underwater off-axis digital hologram imaging
    Flow chart of hologram reconstruction
    Filtering schematic of 4F system
    Relationship between scattering noise intensity and camera receiving angle
    Frequency domain diagram of 4F pinhole filtering system
    Principle of down-sampling image segmentation
    Training process of image denoising
    Underwater off-axis digital holographic imaging experimental setup based on 4F system
    Imaging results at different attenuation lengths. (a)‒(d) Direct imaging; (e)‒(h) 4F filtered off-axis digital holography imaging
    Holographic imaging with or without 4F system at different attenuation lengths. (a)‒(d) Without 4F system; (e)‒(h) with 4F system
    Reconstructed holograms with or without 4F system at different attenuation lengths. (a)‒(d) Without 4F system; (e)‒(h) with 4F system
    Holograms reconstructed at different light intensity ratios and attenuation lengths
    Comparison of evaluation indexes of reconstructed holograms at different light intensity ratios and attenuation lengths. (a) SSIM; (b) PSNR; (c) RMSE
    Holograms reconstructed by different filters at different attenuation lengths. (a) (d) Butterworth low-pass filter; (b) (e) ideal low-pass filter; (c) (f) Gaussian low-pass filter
    Comparison of evaluation indexes of holograms reconstructed by different filters at different attenuation lengths. (a) SSIM; (b) PSNR; (c) RMSE
    Reconstruction results at maximum attenuation length. (a) Attenuation length of 10.4; (b) attenuation length of 10.3
    Noisy and denoised images. (a)(c) Reconstruction images before denoising; (b)(d) reconstructed images after denoising
    • Table 1. Imaging quality evaluation indexes of direct imaging and holographic imaging at different attenuation lengths

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      Table 1. Imaging quality evaluation indexes of direct imaging and holographic imaging at different attenuation lengths

      Attenuation lengthEvaluation index
      NameFig. 9 (a)Fig. 9 (b)Fig. 9 (c)Fig. 9 (d)Fig. 9 (e)Fig. 9 (f)Fig. 9 (g)Fig. 9 (h)
      2.4SSIM0.7690.6310.6550.7660.7810.7530.6770.773
      PSNR /dB8.678.238.978.5313.6711.5212.5313.57
      RMSE81.4282.3378.6982.3164.3865.4864.6361.68
      4.3SSIM0.6530.4550.4030.5030.6440.6640.6330.539
      PSNR /dB6.816.126.636.8910.8711.2312.0311.89
      RMSE94.5293.4792.4191.6381.2183.4282.4381.56
      6.4SSIM0.1030.1070.1120.1330.4080.4210.4930.433
      PSNR /dB3.123.533.563.428.678.238.158.43
      RMSE193.67183.42162.42160.71106.31108.34102.23100.03
      9.3SSIM0.2880.2320.3120.254
      PSNR /dB4.834.674.874.93
      RMSE153.42151.34145.74148.44
    • Table 2. Evaluation indexes of reconstructed holograms with or without 4F system at different attenuation lengths

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      Table 2. Evaluation indexes of reconstructed holograms with or without 4F system at different attenuation lengths

      Attenuation lengthEvaluation index
      NameFig. 11(a)Fig. 11 (b)Fig. 11 (c)Fig. 11 (d)Fig. 11 (e)Fig. 11 (f)Fig. 11 (g)Fig. 11 (h)
      2.4SSIM0.6420.6430.4120.3550.7810.7530.6770.773
      PSNR /dB10.7110.828.616.2313.6711.5212.5313.57
      RMSE88.6586.38102.34123.4764.3865.4864.6361.68
      4.2SSIM0.4390.4930.3150.3140.6440.6640.6330.539
      PSNR /dB8.969.345.655.6110.8711.2312.0311.89
      RMSE106.75102.96115.63122.3981.2183.4282.4381.56
      6.4SSIM0.2040.3050.2970.2170.4080.4210.4930.433
      PSNR /dB4.135.324.784.678.678.238.158.43
      RMSE151.14159.63166.43175.31106.31108.34102.23100.03
      8.2SSIM0.0150.2110.1020.0960.3560.3210.4630.255
      PSNR /dB0.974.222.141.756.136.677.135.03
      RMSE220.13216.75200.33207.43126.41122.73117.25128.79
      9.3SSIM0.0070.0150.0110.0090.2580.2120.3120.254
      PSNR /dB0.310.830.770.674.834.674.874.93
      RMSE217.63211.32213.79215.37133.42151.34145.74148.44
    • Table 3. Evaluation index of reconstructed images

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      Table 3. Evaluation index of reconstructed images

      Attenuation lengthPSNR /dBSSIMRMSE
      10.43.210.095182.66
      10.34.650.175164.23
    • Table 4. Evaluation indexes of denoised images

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      Table 4. Evaluation indexes of denoised images

      Attenuation lengthPSNR /dBSSIMRMSE
      10.46.530.265122.53
      10.37.680.377112.74
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    Quan Liu, Ying Jin, Quanying Wu, Weixuan Yi, Haofan Wang, Guohai Situ. Optimization Method for Underwater Scattering Imaging Based on Off-Axis Digital Holography[J]. Laser & Optoelectronics Progress, 2025, 62(14): 1411002

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    Paper Information

    Category: Imaging Systems

    Received: Jan. 9, 2025

    Accepted: Feb. 4, 2025

    Published Online: Jul. 3, 2025

    The Author Email: Ying Jin (yingjin@siom.ac.cn), Quanying Wu (wqycyh@mail.usts.edu.cn)

    DOI:10.3788/LOP250473

    CSTR:32186.14.LOP250473

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