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

Haima Yang; Zhongyang Jiang; Yu Zhang; Xianglei Hu; Haibin Sun; Fuchun Chen; Jun Li; Jin Liu

doi:10.3788/LOP241589

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

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

Haima Yang^1,2、**, Zhongyang Jiang¹, Yu Zhang¹, Xianglei Hu¹, Haibin Sun², Fuchun Chen², Jun Li¹, and Jin Liu^3、*

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)

Fig. 1. Spectral response range of OV6946

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Fig. 2. System block diagram

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Fig. 3. OV6946 system image acquisition platform

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Fig. 4. Impedance matching and amplifying circuit diagram

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Fig. 5. Online verification of FPGA data conversion

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Fig. 6. Simulation of DDR3 read and write data

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Fig. 7. Video data stream access state machine

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Fig. 8. Sequence picture storage state machine

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Fig. 9. Traditional CLAHE algorithm flowchart

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Fig. 10. Flow chart of the algorithm

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Fig. 11. Resolution card shooting. (a) Shooting the resolution card; (b) enlarged view of a section of the resolution card

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Fig. 12. Spectral detection of the illumination light source. (a) Actual photo of the illumination light source; (b) spectrogram of the illumination light source

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Fig. 13. Comparison of image before and after color correction. (a) Image before correction; (b) image after correction

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Fig. 14. Comparison between OV6922 and OV6946. (a) Image captured by OV6922; (b) image captured by OV6946

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Fig. 15. Comparison of endoscopic image enhancement algorithms. (a) Original drawings; (b) HE; (c) CLAHE; (d) AGCWD; (e) LIME; (f) MSRCR; (g) proposed algorithm

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Table 1. Parameters of each camera module

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Table 1. Parameters of each camera module

Model	OV7740	OV6946	OV6948	OV6922
Band range /nm	400‒720	300‒1100	400‒780	400‒780
Output format	RAW RGB	RAW RGB	RAW RGB	RAW RGB
Lens size /inch	1/5	1/18	1/36	1/18
Image resolution	640×480	400×400	200×200	328×250
Pixel size /（μm×μm）	4.2×4.2	1.75×1.75	1.75×1.75	2.5×2.5
Frame rate /（frame/s）	60	30	30	30

Table 2. OV6946 lens parameters
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Table 2. OV6946 lens parameters
Field of view /（°） Lens aperture /mm Focal length /mm Depth of field /mm Signal line length /mm
120 1.9 0.4 3-30 1500

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 image	HE	CLAHE	AGCWD	LIME	MSRCR	Proposed algorithm
Image 1	7.4686	7.7835	7.6276	6.8847	5.9426	6.4472	7.7075
Image 2	7.2596	7.4331	7.4223	6.3538	6.0342	5.6159	7.7521
Image 3	7.5772	6.6963	7.6412	7.0197	7.0585	6.1832	7.6551
Image 4	7.4049	6.8214	7.4813	6.8912	6.6807	6.1258	7.5113

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 image	HE	CLAHE	AGCWD	LIME	MSRCR	Proposed algorithm
Image 1	7.3295	17.512	20.676	5.6296	14.261	16.187	33.978
Image 2	7.0844	17.879	20.092	5.1502	9.6005	6.6891	28.051
Image 3	11.567	18.553	18.4	7.1053	14.738	6.6527	33.721
Image 4	11.677	22.629	20.536	7.4241	14.024	7.7142	33.567

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 image	HE	CLAHE	AGCWD	LIME	MSRCR	Proposed algorithm
Image 1	3.4269	8.3287	9.6926	2.7108	6.9899	7.8693	16.266
Image 2	3.3158	8.7174	9.4098	2.4723	4.6887	3.1541	13.161
Image 3	5.4124	8.7415	8.5741	3.388	6.9823	3.182	16.026
Image 4	5.4795	10.76	9.6261	3.5592	6.6834	3.71	16.076

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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

Topics

laser devices and laser physics

Lasers and Laser Optics

Laser physics

laser manufacturing

Instrumentation, Measurement and Metrology

Table 1. Parameters of each camera module

Table 1. Parameters of each camera module

Table 2. OV6946 lens parameters

Table 2. OV6946 lens parameters

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

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

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

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

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

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