Retinal vessel delineation using a brain-inspired wavelet transform and random forest

Jiong Zhang, Yuan Chen, Erik J. Bekkers, Meili Wang, Behdad Dashtbozorg, Bart M. ter Haar Romeny

Abstract: This paper presents a supervised retinal vessel segmentation by incorporating vessel filtering and wavelet transform features from orientation scores (OSs), and green intensity. Through an anisotropic wavelet-type transform, a 2D image is lifted to a 3D orientation score in the Lie-group domain of positions and orientations R2⋊S1<math><mrow is="true"><msup is="true"><mi mathvariant="double-struck" is="true">R</mi><mn is="true">2</mn></msup><mo is="true">⋊</mo><msup is="true"><mi is="true">S</mi><mn is="true">1</mn></msup></mrow></math>. Elongated structures are disentangled into their corresponding orientation planes and enhanced via multi-orientation vessel filtering. In addition, scale-selective OSs (in the domain of positions, orientations and scales R2⋊S1×R+<math><mrow is="true"><msup is="true"><mi mathvariant="double-struck" is="true">R</mi><mn is="true">2</mn></msup><mo is="true">⋊</mo><msup is="true"><mi is="true">S</mi><mn is="true">1</mn></msup><mo is="true">×</mo><msup is="true"><mi mathvariant="double-struck" is="true">R</mi><mo is="true">+</mo></msup></mrow></math>) are obtained by adding a scale adaptation to the wavelet transform. Features are optimally extracted by taking maximum orientation responses at multiple scales, to represent vessels of changing calibers. Finally, we train a Random Forest classifier for vessel segmentation. Extensive validations show that our method achieves a competitive segmentation, and better vessel preservation with less false detections compared with the state-of-the-art methods.