# The Little W-Net That Could: State-of-the-Art Retinal Vessel Segmentation with Minimalistic Models Source: [The Little W-Net That Could: State-of-the-Art Retinal Vessel Segmentation with Minimalistic Models]() Collection index: [llms.txt]() Data updated: 2025-10-25T22:32:00.581Z Authors: Adrian Galdran, Andr\\'e Anjos, Jos\\'e Dolz, Hadi Chakor, Herv\\'e Lombaert, Ismail Ben Ayed Published: 2020-09-03T19:59:51.000Z ## Abstract The segmentation of the retinal vasculature from eye fundus images represents one of the most fundamental tasks in retinal image analysis. Over recent years, increasingly complex approaches based on sophisticated Convolutional Neural Network architectures have been slowly pushing performance on well-established benchmark datasets. In this paper, we take a step back and analyze the real need of such complexity. Specifically, we demonstrate that a minimalistic version of a standard U-Net with several orders of magnitude less parameters, carefully trained and rigorously evaluated, closely approximates the performance of current best techniques. In addition, we propose a simple extension, dubbed W-Net, which reaches outstanding performance on several popular datasets, still using orders of magnitude less learnable weights than any previously published approach. Furthermore, we provide the most comprehensive cross-dataset performance analysis to date, involving up to 10 different databases. Our analysis demonstrates that the retinal vessel segmentation problem is far from solved when considering test images that differ substantially from the training data, and that this task represents an ideal scenario for the exploration of domain adaptation techniques. In this context, we experiment with a simple self-labeling strategy that allows us to moderately enhance cross-dataset performance, indicating that there is still much room for improvement in this area. Finally, we also test our approach on the Artery/Vein segmentation problem, where we again achieve results well-aligned with the state-of-the-art, at a fraction of the model complexity in recent literature. All the code to reproduce the results in this paper is released. ## Recorded benchmark results A research result applies to its stated dataset, split, metric and evaluation configuration. Compare like-for-like settings, preserve the metric's unit and direction, and distinguish paper-reported results from independent reproduction. The best result recorded here is not a claim of exhaustive, current global coverage. - [Inflection Count \[median\] Extraction on Rotterdam sets Artery 215 CFIs](): Inflection Count \[median\] Extraction; Rotterdam sets Artery 215 CFIs; MAE: 0.53. - [Tortuosity \[median\] Extraction on Rotterdam sets Artery](): Tortuosity \[median\] Extraction; Rotterdam sets Artery; MAE: 0.0059. - [Vascular Density Extraction on Rotterdam sets Artery 215 CFIs](): Vascular Density Extraction; Rotterdam sets Artery 215 CFIs; MAE: 0.76. - [Vessel Caliber Standard Deviation Extraction on Leuven-Haifa 240 CFIs (Vein)](): Vessel Caliber Standard Deviation Extraction; Leuven-Haifa 240 CFIs (Vein); MAE: 0.74. - [Artery-vein segmentation on HRF-AV](): Artery-vein segmentation; HRF-AV; Dice (Arteries): 50.6. - [Artery-vein segmentation on Les-AV](): Artery-vein segmentation; Les-AV; Dice (Arteries): 61.8. - [Vessel Segmentation on ChaseDB](): Vessel segmentation; ChaseDB; Dice Coefficient: 73.2. - [Artery-vein segmentation on Leuven-Haifa](): Artery-vein segmentation; Leuven-Haifa; Dice (Arteries): 56.9. - [Artery-vein segmentation on Rotterdam](): Artery-vein segmentation; Rotterdam; Dice (Arteries): 63.5. - [Bifurcation Angles \[mean\] Extraction on Rotterdam sets Artery (215 CFIs)](): Bifurcation Angles \[mean\] Extraction; Rotterdam sets Artery 215 CFIs; MAE: 9.51. - [Bifurcation Angles \[mean\] Extraction on Rotterdam sets Vein 215 CFIs](): Bifurcation Angles \[mean\] Extraction; Rotterdam sets Vein 215 CFIs; MAE: 7.71. - [Bifurcation Angles \[median\] Extraction on Rotterdam sets Artery 215 CFIs](): Bifurcation Angles \[median\] Extraction; Rotterdam sets Artery 215 CFIs; MAE: 8.97. - [Bifurcation Angles \[median\] Extraction on Rotterdam sets Vein 215 CFIs](): Bifurcation Angles \[median\] Extraction; Rotterdam sets Vein 215 CFIs; MAE: 5.96. - [Bifurcation Detection on Leuven-Haifa Artery 240 CFIs](): Bifurcation Detection; Leuven-Haifa Artery 240 CFIs; MAE: 7.62. - [Bifurcation Detection on Leuven-Haifa Vein 240 CFIs](): Bifurcation Detection; Leuven-Haifa Vein 240 CFIs; MAE: 9.11. - [Central Retinal Equivalent (CRE) Extraction on Rotterdam sets Artery 215 CFIs](): Central Retinal Equivalent (CRE) Extraction; Rotterdam sets Artery 215 CFIs; MAE: 3.1. - [Central Retinal Equivalent (CRE) Extraction on Rotterdam sets Vein 215 CFIs](): Central Retinal Equivalent (CRE) Extraction; Rotterdam sets Vein 215 CFIs; MAE: 3.79. - [Central Retinal Equivalent (CRE) Extraction on Leuven-Haifa Artery 240 CFIs](): Central Retinal Equivalent (CRE) Extraction; Leuven-Haifa Artery 240 CFIs; MAE: 2.98. - [Central Retinal Equivalent (CRE) Extraction on Leuven-Haifa Vein 240 CFIs](): Central Retinal Equivalent (CRE) Extraction; Leuven-Haifa Vein 240 CFIs; MAE: 4.7. - [Curvature \[median\] Extraction on Rotterdam sets Artery](): Curvature \[median\] Extraction; Rotterdam sets Artery; MAE: 1.34. - [Curvature \[median\] Extraction on Rotterdam sets Vein 215 CFIs](): Curvature \[median\] Extraction; Rotterdam sets Vein 215 CFIs; MAE: 1.44. - [Inflection Count \[median\] Extraction on Rotterdam sets 215 CFIs Vein](): Inflection Count \[median\] Extraction; Rotterdam sets 215 CFIs Vein; MAE: 0.6. - [Length-Weighted Tortuosity Extraction on Leuven-Haifa 240 CFIs Artery](): Length-Weighted Tortuosity Extraction; Leuven-Haifa 240 CFIs (Artery); MAE: 0.06. - [Length-Weighted Tortuosity Extraction on Leuven-Haifa Vein 240 CFIs](): Length-Weighted Tortuosity Extraction; Leuven-Haifa Vein 240 CFIs; MAE: 0.054. - [Mean Bifurcation Angle Extraction on Leuven-Haifa Artery 240 CFIs](): Mean Bifurcation Angle Extraction; Leuven-Haifa Artery 240 CFIs; MAE: 11.58. - [Mean Bifurcation Angle Extraction on Leuven-Haifa Vein 240 CFIs](): Mean Bifurcation Angle Extraction; Leuven-Haifa Vein 240 CFIs; MAE: 10.63. - [Median Bifurcation Angle Extraction on Leuven-Haifa 240 CFIs](): Median Bifurcation Angle Extraction; Leuven-Haifa 240 CFIs (Artery); MAE: 10.75. - [Median Bifurcation Angle Extraction on Leuven-Haifa 240 CFIs (Vein)](): Median Bifurcation Angle Extraction; Leuven-Haifa 240 CFIs (Vein); MAE: 9.51. - [Median Curvature Extraction on Leuven-Haifa Artery 240 CFIs](): Median Curvature Extraction; Leuven-Haifa Artery 240 CFIs; MAE: 1.37. - [Median Curvature Extraction on Leuven-Haifa Vein 240 CFIs](): Median Curvature Extraction; Leuven-Haifa Vein 240 CFIs; MAE: 1.34. - [Median Inflection Count Extraction on Leuven-Haifa Artery 240 CFIs](): Median Inflection Count Extraction; Leuven-Haifa Artery 240 CFIs; MAE: 0.69. - [Median Inflection Count Extraction on Leuven-Haifa Vein 240 CFIs](): Median Inflection Count Extraction; Leuven-Haifa Vein 240 CFIs; MAE: 0.76. - [Median Tortuosity Extraction on Leuven-Haifa Artery 240 CFIs](): Median Tortuosity Extraction; Leuven-Haifa Artery 240 CFIs; MAE: 0.008. - [Median Tortuosity Extraction on Leuven-Haifa Vein 240 CFIs](): Median Tortuosity Extraction; Leuven-Haifa Vein 240 CFIs; MAE: 0.0064. - [Median Vessel Caliber Extraction on Leuven-Haifa Artery 240 CFIs](): Median Vessel Caliber Extraction; Leuven-Haifa Artery 240 CFIs; MAE: 1.73. - [Median Vessel Caliber Extraction on Leuven-Haifa Vein 240 CFIs](): Median Vessel Caliber Extraction; Leuven-Haifa Vein 240 CFIs; MAE: 2.24. - [Number of Bifurcations Extraction on Rotterdam sets Artery 215 CFIs](): Number of Bifurcations Extraction; Rotterdam sets Artery 215 CFIs; MAE: 12.59. - [Number of Bifurcations Extraction on Rotterdam sets 215 CFIs Vein](): Number of Bifurcations Extraction; Rotterdam sets 215 CFIs Vein; MAE: 13.48. - [Temporal Angle Extraction on Rotterdam sets 215 CFIs Artery](): Temporal Angle Extraction; Rotterdam sets 215 CFIs Artery; MAE: 8.63. - [Temporal Angle Extraction on Rotterdam sets 215 CFIs Vein](): Temporal Angle Extraction; Rotterdam sets 215 CFIs Vein; MAE: 8.29. - [Temporal Angle Extraction on Leuven-Haifa Artery 240 CFIs](): Temporal Angle Extraction; Leuven-Haifa Artery 240 CFIs; MAE: 10.48. - [Temporal Angle Extraction on Leuven-Haifa Vein 240 CFIs](): Temporal Angle Extraction; Leuven-Haifa Vein 240 CFIs; MAE: 11.68. - [Tortuosity \[length-weighted\] Extraction on Rotterdam sets Artery 215 CFIs](): Tortuosity \[length-weighted\] Extraction; Rotterdam sets Artery 215 CFIs; MAE: 0.038. - [Tortuosity \[length-weighted\] Extraction on Rotterdam sets Vein 215 CFIs](): Tortuosity \[length-weighted\] Extraction; Rotterdam sets Vein 215 CFIs; MAE: 0.033. - [Tortuosity \[median\] Extraction on Rotterdam sets Vein 215 CFIs](): Tortuosity \[median\] Extraction; Rotterdam sets Vein 215 CFIs; MAE: 0.0059. - [Vascular Density Extraction on Rotterdam sets Vein 215 CFIs](): Vascular Density Extraction; Rotterdam sets Vein 215 CFIs; MAE: 1.12. - [Vascular Density Extraction on Leuven-Haifa Artery 240 CFIs](): Vascular Density Extraction; Leuven-Haifa Artery 240 CFIs; MAE: 1.42. - [Vascular Density Extraction on Leuven-Haifa Vein 240 CFIs](): Vascular Density Extraction; Leuven-Haifa Vein 240 CFIs; MAE: 1.31. - [Vessel Caliber \[median\] Extraction on Rotterdam sets Artery 215 CFIs](): Vessel Caliber \[median\] Extraction; Rotterdam sets Artery 215 CFIs; MAE: 1.36. - [Vessel Caliber \[median\] Extraction on Rotterdam sets (215 CFIs) - Vein](): Vessel Caliber \[median\] Extraction; Rotterdam sets 215 CFIs Vein; MAE: 1.38. - [Vessel Caliber \[std\] Extraction on Rotterdam sets Artery 215 CFIs](): Vessel Caliber \[std\] Extraction; Rotterdam sets Artery 215 CFIs; MAE: 0.9. - [Vessel Caliber \[std\] Extraction on Rotterdam sets 215 CFIs Vein](): Vessel Caliber \[std\] Extraction; Rotterdam sets 215 CFIs Vein; MAE: 0.79. - [Vessel Caliber Standard Deviation Extraction on Leuven-Haifa 240 CFIs (Artery)](): Vessel Caliber Standard Deviation Extraction; Leuven-Haifa 240 CFIs (Artery); MAE: 0.65. - [Vessel Segmentation on DRHAGIS](): Vessel segmentation; DRHAGIS; Dice Score: 67.2. - [Vessel segmentation on Leuven-Haifa](): Vessel segmentation; Leuven-Haifa; Dice Score: 71.3. - [Vessel Segmentation on Rotterdam](): Vessel segmentation; Rotterdam; Dice Score: 74.5. - [Vessel Segmentation on HRF](): Vessel segmentation; HRF; Dice Score: 0.573. - [Vessel Segmentation on FIVES](): Vessel segmentation; FIVES; Dice Score: 75.6. ## Original sources and implementation [Original paper]() [PDF]()