In this paper we consider the problem of blood vessel segmentation in retinal images. After enhancing the retinal image we use green channel of images for segmentation as it provides better discrimination between vessels and background. We consider the negative of retinal green channel image as a topographical surface and extract ridge points on this surface. The points with this property are l...

The proposed ridge features are composed of four elements: ridge count, ridge length, ridge curvature direction, and ridge type. For extracting ridge features, we also define the ridge-based coordinate system in a skeletonized image With the proposed ridge features and conventional minutiae features(minutiae type, orientation, and position), we propose a novel matching scheme using a breadth-fi...

GaP terahertz (THz) two-dimensional (2D) photonic crystal (PC) waveguides with line defects were fabricated using inductively-coupled plasma reactive-ion etching (ICP-RIE) in Ar/Cl2 gas chemistries. THz-wave generation from the fabricated PC waveguides was demonstrated under collinear phase-matched difference-frequency generation (DFG), using Cr:Forsterite (Cr:F) lasers as the incident source. ...

A new process to produce orientation-patterned gallium phosphide (OP-GaP) on GaAs with almost perfectly parallel domain boundaries is presented. Taking advantage of the chemical selectivity between phosphides and arsenides, OP-GaP processed into suspended shallow-ridge waveguides. Efficient second-harmonic generation from telecom wavelengths achieved in both Type-I Type-II polarisation configur...

BACKGROUND AND PURPOSE The bifurcation regions of the major human cerebral arteries are vulnerable to the formation of saccular aneurysms. A consistent feature of these bifurcations is a discontinuity of the tunica media at the apex of the flow divider. The objective was to measure the 3-dimensional geometry of these medial gaps or "medial defects." METHODS Nineteen bifurcations and 2 junctio...