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Acta Optica Sinica, Volume. 43, Issue 5, 0511002(2023)

Human Eye Autofocus and Pupil Center Auto-Alignment System

Luhan Wang1,2, Yan Gong2,3、*, Yanwei Zhang2, Song Lang2,4, and Hanqing Zheng2
Author Affiliations
  • 1Life Sciences and Medicine, School of Biomedical Engineering (Suzhou), University of Science and Technology of China, Suzhou 215163, Jiangsu, China
  • 2Medical Optical Research Laboratory, Suzhou Institute of Biomedical Engineering Technology, Chinese Academy of Sciences, Suzhou 215163, Jiangsu, China
  • 3Jinan Guoke Medical Technology Development Co., Ltd., Jinan 250102, Shandong, China
  • 4Shenyang Guoke Medical Technology Development Co., Ltd., Shenyang 110167, Liaoning, China
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    AbstractGet PDF(in Chinese)
    Figures&Tables (15)
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    References (22)
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    Figures & Tables(15)
    Structure of human eye auto-focus and pupil center auto-alignment device

    Fig. 1. Structure of human eye auto-focus and pupil center auto-alignment device

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    Schematic of optical path of imaging module

    Fig. 2. Schematic of optical path of imaging module

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    Flowchart of pupil center positioning and alignment algorithm

    Fig. 3. Flowchart of pupil center positioning and alignment algorithm

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    Collected image of human eye and ROI image. (a) Original image of human eye; (b) ROI image of pupil

    Fig. 4. Collected image of human eye and ROI image. (a) Original image of human eye; (b) ROI image of pupil

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    Grayscale histogram distributions before and after extraction of ROI. (a) Grayscale histogram distribution of original image; (b) grayscale histogram distribution of ROI

    Fig. 5. Grayscale histogram distributions before and after extraction of ROI. (a) Grayscale histogram distribution of original image; (b) grayscale histogram distribution of ROI

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    ROI image after threshold segmentation. (a) Image after T1 threshold segmentation; (b) image after T2 threshold segmentation

    Fig. 6. ROI image after threshold segmentation. (a) Image after T1 threshold segmentation; (b) image after T2 threshold segmentation

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    Schematic diagrams of pupil center and optical axis center. (a) Pupil identification and center point; (b) optical axis ellipse fitting and center point

    Fig. 7. Schematic diagrams of pupil center and optical axis center. (a) Pupil identification and center point; (b) optical axis ellipse fitting and center point

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    Schematic diagram of relative position of pupil center and optical axis

    Fig. 8. Schematic diagram of relative position of pupil center and optical axis

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    Schematic diagrams of defocus sequence-1 of human eyes. (a) 5th image of sequence; (b) 9th image of sequence; (c) 13th image of sequence; (d) 17th image of sequence; (e) 21st image of sequence

    Fig. 9. Schematic diagrams of defocus sequence-1 of human eyes. (a) 5th image of sequence; (b) 9th image of sequence; (c) 13th image of sequence; (d) 17th image of sequence; (e) 21st image of sequence

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    Normalized sharpness evaluation curves of human eye defocused image sequences. (a) Sequence 1; (b) sequence 2;(c) sequence 3; (d) sequence 4

    Fig. 10. Normalized sharpness evaluation curves of human eye defocused image sequences. (a) Sequence 1; (b) sequence 2;(c) sequence 3; (d) sequence 4

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    Partial images of sequence 4 in human eye defocused image. (a) 8th image of sequence; (b) 9th image of sequence

    Fig. 11. Partial images of sequence 4 in human eye defocused image. (a) 8th image of sequence; (b) 9th image of sequence

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    Error between pupil center coordinates obtained by three algorithms and manually calibrated pupil center coordinates

    Fig. 12. Error between pupil center coordinates obtained by three algorithms and manually calibrated pupil center coordinates

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    Processing results of algorithm in this paper under complex conditions. (a) Dark light condition; (b) bright light condition; (c)(d) partial occlusion of pupil

    Fig. 13. Processing results of algorithm in this paper under complex conditions. (a) Dark light condition; (b) bright light condition; (c)(d) partial occlusion of pupil

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    • Table 1. Average performance indexes of evaluation curves of out-of-focus sequences 1-4 of human eye images

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      Table 1. Average performance indexes of evaluation curves of out-of-focus sequences 1-4 of human eye images

      Evaluation functionTPF /msRFsenUnimodalityAccuracy
      FMTG13.093.5310.329√√
      Brenner14.12.8000.188——
      Tenengrad42.81.5610.114√√
      SMD16.11.1380.058××
      Laplace13.81.1100.026××
      Vollaths15.71.2040.050××
      Variance15.51.2780.053××

    • Table 2. Average computation time, accuracy, and average error of three algorithms under experimental images

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      Table 2. Average computation time, accuracy, and average error of three algorithms under experimental images

      MethodAverage time /msAccuracy /%Average error /pixel
      LPC10.297.141.4
      Improved Hough584.753.333.3
      Hough5100.414.298.4
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    Luhan Wang, Yan Gong, Yanwei Zhang, Song Lang, Hanqing Zheng. Human Eye Autofocus and Pupil Center Auto-Alignment System[J]. Acta Optica Sinica, 2023, 43(5): 0511002

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    Paper Information

    Category: Imaging Systems

    Received: Sep. 13, 2022

    Accepted: Oct. 17, 2022

    Published Online: Feb. 27, 2023

    The Author Email: Gong Yan (gongy@sibet.ac.cn)

    DOI:10.3788/AOS221703

    Topics

    laser devices and laser physics
    Lasers and Laser Optics
    Laser physics
    laser manufacturing
    Instrumentation, Measurement and Metrology