[2] [2] BALASUBRAMANIAN K, ANANTHAMOORTHY N P. Ro- bust retinal blood vessel segmentation using convolutional neural network and support vector machine[J].Journal of Ambient Intelligence and Humanized Computing,2021,12(3):3559-3569.

[3] [3] BENGANI S,VADIVEL S.Automatic segmentation of optic disc in retinal fundus images using semi-supervised deep learning[J].Multimedia Tools and Applications,2021,80(3):3443-3468.

[4] [4] SAMUEL P M,VEERAMALAI T.Review on retinal blood vessel segmentation an algorithmic perspective[J].International Journal of Biomedical Engineering and Technology,2020,34(1):75-105.

[6] [6] SARHAN A,ROKNE J,ALHAJJ R,et al.Transfer learning through weighted loss function and group normalization for vessel segmentation from retinal images［C］//25th International Conference on Pattern Recognition,January 10-15,2021,Milan,Italy.New York:IEEE,2021:9211-9218.

[7] [7] KANDEL I,CASTELLI M.Transfer learning with convolutional neural networks for diabetic retinopathy image classification.A review[J].Applied Sciences,2020,10(6):1-24.

[8] [8] ZHANG J,ZHANG Y,XU X.Pyramid U-Net for retinal vessel segmentation［C］//IEEE International Conference on Acoustics,Speech and Signal Processing,June 6-11,2021,Toronto,ON,Canada.New York:IEEE,2021:1125-1129.

[9] [9] JHA D,RIEGLER M A,JOHANSEN D,et al.DoubleU-Net:a deep convolutional neural network for medical image segmentation［C］//33rd International Symposium on Computer-Based Medical Systems,June 22-24,2020,Rochester,Minnesota,USA.New York:IEEE,2020:558-564.

[11] [11] WANG Q,WU B,ZHU P,et al.ECA-Net:efficient channel attention for deep convolutional neural networks［C］//IEEE/CVF Conference on Computer Vision and Pattern Recognition,June 13-19,2020,Seattle,WA,USA.New York:IEEE.2020:11531-11539.

[12] [12] WOO S,PARK J,LEE J Y,et al.CBAM:convolutional block attention module［C］//European Conference on Computer Vision,September 8-14,2018,Munich,Germany.Berlin:Springer,2018:3-19.

[13] [13] LIAN X,PANG Y,HAN J,et al.Cascaded hierarchical atrous spatial pyramid pooling module for semantic segmentation [J].Pattern Recognition,2021,110(4):107622.

[14] [14] HU J,SHEN L,ALBANIE S,et al.Squeeze-and-excitation networks[J]. IEEE Transactions on Pattern Analysis and Machine Intelligence,2018,42(8):2011-2023.

[15] [15] GU R,WANG G,SONG T,et al.CA-Net:comprehensive attention convolutional neural networks for explainable medical image segmentation[J].IEEE Transactions on Medical Imaging,2021,40(2):699-711.

[16] [16] AZAD R,ASADI-AGHBOLAGHI M,FATHY M, et al.Bi-directional ConvLSTM U-Net with densley connected convolutions［C］//IEEE/CVF International Conference on Computer Vision Workshops,October 27-28,2019,Seoul,Korea (South).New York:2019:406-415.

[17] [17] TANG Y,RUI Z,YAN C,et al.ResWnet for retinal small vessel segmentation[J].IEEE Access,2020,8:198265-198274.

[18] [18] LI H,WANG Y K,WAN C,et al.MAU-Net:a retinal vessels segmentation method［C］//42nd Annual International Conference of the IEEE Engineering in Medicine & Biology Society,July 20-24,2020,Montreal,QC,Canada.New York:IEEE,2020:1958-1961.

[19] [19] LV Y,MA H,LI J,et al.Attention guided U-Net with atrous convolution for accurate retinal vessels segmentation[J].IEEE Access,2020,8:32826-32839.

[20] [20] LIN Z,HUANG J,CHEN Y,et al.A high resolution representation network with multi-path scale for retinal vessel segmentation[J].Computer Methods and Programs in Biomedicine,2021,208:106206.

[21] [21] JIN Q,MENG Z,PHAM T D,et al.DUNet:a deformable network for retinal vessel segmentation[J].Knowledge Based Systems,2019,178:149-162.

[22] [22] WU Y,XIA Y,SONG Y,et al.Vessel-Net:retinal vessel segmentation under multi-path supervision［C］//International Conference on Medical Image Computing and Computer Assisted Intervention,October 13-17,2019,Shenzhen,China.Berlin:Springer-Verlarg,2019:264-272.

[23] [23] WANG D,HAYTHAM A,POTTENBURGH J,et al.Hard attention net for automatic retinal vessel segmentation[J].IEEE Journal of Biomedical and Health Informatics,2020,24(12):3384-3396．

[24] [24] YUAN Y,ZHANG L,WANG L,et al.Multi-level attention network for retinal vessel segmentation[J].IEEE Journal of Biomedical and Health Informatics,2021,40(2):588-609.

[25] [25] WU Y,XIA Y,SONG Y,et al.NFN+:a novel network followed network for retinal vessel segmentation[J].Neural Networks,2020,126:153-162.