Speckle Reduction with Attenuation Compensation for Skin OCT Images Enhancement

The enhancement of skin image in optical coherence tomography (OCT) imaging can help dermatologists to investigate tissue layers more accurately, hence the more efficient diagnosis. In this paper, we propose an image enhancement technique including speckle reduction, attenuation compensation and cleaning to improve the quality of OCT skin images. A weighted median filter is designed to reduce the level of speckle noise while preserving the contrast. A novel border detection technique is designed to outline the main skin layers, stratum corneum, epidermis and dermis. A model of the light attenuation is then used to estimate the absorption coefficient of epidermis and dermis layers and compensate the brightness of the structures at deeper levels. The undesired part of the image is removed using a simple cleaning algorithm. The performance of the algorithm has been evaluated visually and numerically using the commonly used no-reference quality metrics. The results shows an improvement in the quality of the images. Keywords: Optical coherence tomography (OCT), Skin, Image enhancement, Speckle reduction, Attenuation compensation

Anti-Spoof Reliable Biometry of Fingerprints Using En-Face Optical Coherence Tomography

Optical coherence tomography (OCT) is a relatively new imaging technology which can produce high-reso- lution images of three-dimensional structures. OCT has been mainly used for medical applications such as for ophthalmology and dermatology. In this study we demonstrate its capability in providing much more re- liable biometry identification of fingerprints than conventional methods. We prove that OCT can serve se- cure control of genuine fingerprints as it can detect if extra layers are placed above the finger. This can pre- vent with a high probability, intruders to a secure area trying to foul standard systems based on imaging the finger surface. En-Face OCT method is employed and recommended for its capability of providing not only the axial succession of layers in depth, but the en-face image that allows the traditional pattern identification. Another reason for using such OCT technology is that it is compatible with dynamic focus and therefore can provide enhanced transversal resolution and sensitivity. Two En-Face OCT systems are used to evaluate the need for high resolution and conclusions are drawn in terms of the most potential commercial route to ex- ploitation

Stress-Strain Constitutive Material Models for Hybrid Steel Fiber Reinforced Concrete

Recent advancements in fiber reinforced concrete (FRC) technology has led to the development of fibrous concrete composites, comprised of fibers with different material and/or geometry, commonly known as hybrid FRC. In one type of hybrid FRC composites, advantageous behaviors of fibers of the same material but with different geometries are gathered in a single FRC mix. The aim of this paper is to develop and validate stress-strain relationships for hybrid steel FRC composites. Six different steel FRC mixes are produced and characterization tests are conducted. Cube, cylindrical and beam specimens are produced for each characterization test corresponding to each of the Steel FRC (SFRC) composites. In this regard, an experimental program is performed to determine the basic engineering properties of SFRC composites using standard compressive, splitting tensile and three-point bending tests. The prescribed procedure of the RILEM guideline, originally developed for non-hybrid FRC, is followed using the obtained experimental results to develop stress-strain behavior models for the SFRC mixes. To validate results for the hybrid SFRC composites, numerical simulations of the 3-point bending tests were performed and compared to that of corresponding experimental results. The results indicated that the proposed stress-strain relationships yield acceptable results for characterizing the behavior of hybrid SFRC composites