Background: The morphological characteristics of sperm are essential for assessing sperm quality, which partially influences reproductive efficiency variables such as litter size in sows. Recently, deep-learning-based object detection algorithms have been explored to detect and classify sperm morphological features, with the training of these models requiring sperm microscopy image data. The performance of these models in detecting morphological features was significantly affected by the size of the dataset and the image quality of the images. Methods: This study proposed a deep-learning-based super-resolution (SR) algorithm to enhance the quality of sperm microscope images. The model was trained using a dataset consisting of high-resolution (HR) original and low-resolution (LR) images generated by downscaling the original images through bicubic interpolation. The SR results of the test dataset were compared with those of the original HR images to evaluate their performances using the peak signal-to-noise ratio (PSNR) and structural similarity index measure (SSIM). Statistical analyses were conducted to examine the performance differences based on the training models and dataset types. Results: This study indicated that the SR images showed no significant differences in PSNR (p = 0.9740) and SSIM (p = 0.9864) compared with the original HR images in same magnification. Moreover, increased processing speed was observed with reductions in model hyperparameters. While processing SR images improved spatial resolution across various microscopic magnifications, the overall image quality did not exceed that of the original HR images. Conclusions: SR models applied to sperm microscopy images outperformed conventional SR algorithms. These findings suggest that SR algorithms hold promise for improving the quality of LR microscopic images in future deep-learning-based object-detection algorithms.

ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
    Sperm preparation
    Data preprocessing
    Model selection and hyper-parameter
    Evaluation metrics
    Statistical analysis
RESULTS
    SR of sperm microscopic images at the same magnification
    Super-resolution of sperm microscopic images at thedifferent magnification
DISCUSSION
CONCLUSION
REFERENCES

• Jaeuk Cho(College of Animal Life Sciences, Kangwon National University, Chuncheon 24341, Korea)
• Eunju Seok(College of Animal Life Sciences, Kangwon National University, Chuncheon 24341, Korea)
• Sang-Hee Lee(College of Animal Life Sciences, Kangwon National University, Chuncheon 24341, Korea, School of ICT, University of Tasmania, Hobart 7005, Australia) Corresponding author