Laser & Optoelectronics Progress, Volume. 61, Issue 20, 2011015(2024)

Wide-Spectrum CMOS Endoscopic Imaging Enhancement System Based on Pangu FPGA Driver (Invited)

Haima Yang1,2、**, Zhongyang Jiang1, Yu Zhang1, Xianglei Hu1, Haibin Sun2, Fuchun Chen2, Jun Li1, and Jin Liu3、*
Author Affiliations
  • 1School of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
  • 2Key Laboratory of Space Active Opto-Electronics Technology, Chinese Academy of Sciences, Shanghai 201800, China
  • 3College of Electronic and Electrical Engineering, Shanghai University of Engineering Science, Shanghai 201620, China
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    Figures & Tables(20)
    Spectral response range of OV6946
    System block diagram
    OV6946 system image acquisition platform
    Impedance matching and amplifying circuit diagram
    Online verification of FPGA data conversion
    Simulation of DDR3 read and write data
    Video data stream access state machine
    Sequence picture storage state machine
    Traditional CLAHE algorithm flowchart
    Flow chart of the algorithm
    Resolution card shooting. (a) Shooting the resolution card; (b) enlarged view of a section of the resolution card
    Spectral detection of the illumination light source. (a) Actual photo of the illumination light source; (b) spectrogram of the illumination light source
    Comparison of image before and after color correction. (a) Image before correction; (b) image after correction
    Comparison between OV6922 and OV6946. (a) Image captured by OV6922; (b) image captured by OV6946
    Comparison of endoscopic image enhancement algorithms. (a) Original drawings; (b) HE; (c) CLAHE; (d) AGCWD; (e) LIME; (f) MSRCR; (g) proposed algorithm
    • Table 1. Parameters of each camera module

      View table

      Table 1. Parameters of each camera module

      ModelOV7740OV6946OV6948OV6922
      Band range /nm400‒720300‒1100400‒780400‒780
      Output formatRAW RGBRAW RGBRAW RGBRAW RGB
      Lens size /inch1/51/181/361/18
      Image resolution640×480400×400200×200328×250
      Pixel size /(μm×μm)4.2×4.21.75×1.751.75×1.752.5×2.5
      Frame rate /(frame/s)60303030
    • Table 2. OV6946 lens parameters

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      Table 2. OV6946 lens parameters

      Field of view /(°)Lens aperture /mmFocal length /mmDepth of field /mmSignal line length /mm
      1201.90.43-301500
    • Table 3. Information entropy of different images processed by different algorithms

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      Table 3. Information entropy of different images processed by different algorithms

      Image No.Original imageHECLAHEAGCWDLIMEMSRCRProposed algorithm
      Image 17.46867.78357.62766.88475.94266.44727.7075
      Image 27.25967.43317.42236.35386.03425.61597.7521
      Image 37.57726.69637.64127.01977.05856.18327.6551
      Image 47.40496.82147.48136.89126.68076.12587.5113
    • Table 4. Average gradients of different images processed by different algorithms

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      Table 4. Average gradients of different images processed by different algorithms

      Image No.Original imageHECLAHEAGCWDLIMEMSRCRProposed algorithm
      Image 17.329517.51220.6765.629614.26116.18733.978
      Image 27.084417.87920.0925.15029.60056.689128.051
      Image 311.56718.55318.47.105314.7386.652733.721
      Image 411.67722.62920.5367.424114.0247.714233.567
    • Table 5. Local contrast of different images processed by different algorithms

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      Table 5. Local contrast of different images processed by different algorithms

      Image No.Original imageHECLAHEAGCWDLIMEMSRCRProposed algorithm
      Image 13.42698.32879.69262.71086.98997.869316.266
      Image 23.31588.71749.40982.47234.68873.154113.161
      Image 35.41248.74158.57413.3886.98233.18216.026
      Image 45.479510.769.62613.55926.68343.7116.076
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    Haima Yang, Zhongyang Jiang, Yu Zhang, Xianglei Hu, Haibin Sun, Fuchun Chen, Jun Li, Jin Liu. Wide-Spectrum CMOS Endoscopic Imaging Enhancement System Based on Pangu FPGA Driver (Invited)[J]. Laser & Optoelectronics Progress, 2024, 61(20): 2011015

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    Paper Information

    Category: Imaging Systems

    Received: Jul. 1, 2024

    Accepted: Jul. 29, 2024

    Published Online: Nov. 6, 2024

    The Author Email: Yang Haima (snowyhm@usst.edu.cn), Liu Jin (liujin@sues.edu.cn)

    DOI:10.3788/LOP241589

    CSTR:32186.14.LOP241589

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