Imaging comparison experiment of an underwater imaging system with a semiconductor white laser, a monochromatic laser and an LED white light as the light source
doi: 10.37188/CO.EN.2022-0012
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摘要:
为了解决现阶段开展水下探测工作时存在的照明距离短、光谱范围窄等问题,建立了水下半导体白激光成像系统,并对该系统在不同光源及不同条件下采集图像的质量进行分析。将基于红绿蓝(RGB)三基色半导体激光器合成的功率为220 mW、色温为6469 K的白激光作为水下照明光源,分别与红、绿、蓝三种单色激光及LED白光光源在不同条件下的水下成像效果进行对比。对于不同水下光源采集的图像,使用不同算法对其进行处理、分析及质量评价。实验结果表明:半导体白激光作为水下光源,采集的图像不仅在细节信息及结构完整性上优于LED白光光源,同时在目标物色彩还原度以及边缘特征信息完整度方面也优于单色激光。半导体白激光具有能量集中、显色性强、光照度高的优势,其光源性能可满足水下低照度的成像要求,在相同的成像系统及成像距离下可获得真实性更强、质感更好、目标物特征信息更多的图像。
Abstract:To solve the problems of short illumination distance and narrow spectral range in the current underwater detection technology, an underwater semiconductor white laser imaging system was established. The quality of the images captured by the system under different light sources and different conditions was studied. A white laser with a power of 220 mW and a color temperature of 6469 K synthesized by an RGB semiconductor laser is used as the underwater lighting source, which is respectively compared with three RGB monochromatic lasers and an LED white light source under different conditions. For these images, different algorithms are used to process, analyze and evaluate their quality. The results indicate that when the white laser is used as the underwater light source, the collected image is not only better than that with the LED white light source with respect to information detail and structural integrity, but also better than the monochrome laser in color reproduction of the target and the integrity of the edge feature information. The semiconductor white laser has the advantages of concentrated energy, strong color rendering, and high illuminance, and its light source performance can meet the requirements of underwater low-illumination imaging. With the same imaging system and imaging distance, images with stronger authenticity, better texture and more target feature information can be obtained.
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Table 1. Relevant optical parameters of the LED white light source
LED1 LED2 Color temperature/K 7261 5846 Dominant wavelength/nm 477.9 518.9 Color rendering index/Ra 63 64.9 R proportion/(%) 11.7 11.8 G proportion/(%) 86.4 86.2 B proportion/(%) 1.8 2 Table 2. Results of Peak Signal to Noise Ratio (PSNR)
LED1 object A/B LED2 object A/B white laser object A/B CLAHE 12.8346/14.5588 13.1192/16.5358 20.1845/20.4774 Laplacian
Pyramid
Fusion18.9785/17.0071 17.8455/13.0359 19.0232/18.9562 F-C 12.2237/12.9728 12.3596/11.9641 17.0214/17.6895 C-F 12.0095/11.7048 11.5700/10.8762 17.1908/16.0493 Table 3. Results of Structural Similarity Image Integnity(SSIM)
LED1 object A/B LED2 object A/B white laser object A/B CLAHE 0.8416/0.7122 0.7904/0.8709 0.8230/0.9070 Laplacian
Pyramid
Fusion0.9279/0.9251 0.9249/0.9291 0.9465/0.9398 F-C 0.8088/0.6590 0.7510/0.8058 0.7550/0.8749 C-F 0.8271/0.5615 0.7610/0.7392 0.7687/0.8184 -
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