Computer-aided detection and quantification in glistenings on intra-ocular lenses

Multimedia Tools and Applications - The artificial intraocular lens (IOL) is inserted to replaced the crystalline lens of the human eye after cataract surgery or refraction clear lens extraction....     

Quantitative Analysis of X-ray Lithographic Pores by SEM Image Processing

Arrays of regular macropores in electronic, magnetic, photonic and sensing devices can be patterned by X-ray lithography. Such structures inevitably contain some irregularity and require time-consuming pattern inspections. In this work, a pattern inspection by intensity-based digital image processing procedure is proposed and tested on scanning electron microscopy images of porous SU-8 polymer resist. The Otsu’s thresholding converted grayscale to binary images and the closing morphology algorithm was applied to reduce noise in the images. The Canny edge detector was used to identify the contour of each pore by detecting abrupt intensity changes in the binary image. Pores were detected and their sizes were subsequently evaluated. The morphological distributions analyzed by this procedure are comparable to those carried out by the one-by-one human inspection.     

An approach to localize the retinal blood vessels using bit planes and centerline detection

The change in morphology, diameter, branching pattern or tortuosity of retinal blood vessels is an important indicator of various clinical disorders of the eye and the body. This paper reports an automated method for segmentation of blood vessels in retinal images. A unique combination of techniques for vessel centerlines detection and morphological bit plane slicing is presented to extract the blood vessel tree from the retinal images. The centerlines are extracted by using the first order derivative of a Gaussian filter in four orientations and then evaluation of derivative signs and average derivative values is performed. Mathematical morphology has emerged as a proficient technique for quantifying the blood vessels in the retina. The shape and orientation map of blood vessels is obtained by applying a multidirectional morphological top-hat operator with a linear structuring element followed by bit plane slicing of the vessel enhanced grayscale image. The centerlines are combined with these maps to obtain the segmented vessel tree. The methodology is tested on three publicly available databases DRIVE, STARE and MESSIDOR. The results demonstrate that the performance of the proposed algorithm is comparable with state of the art techniques in terms of accuracy, sensitivity and specificity.     

An ensemble classification-based approach applied to retinal blood vessel segmentation

This paper presents a new supervised method for segmentation of blood vessels in retinal photographs. This method uses an ensemble system of bagged and boosted decision trees and utilizes a feature vector based on the orientation analysis of gradient vector field, morphological transformation, line strength measures, and Gabor filter responses. The feature vector encodes information to handle the healthy as well as the pathological retinal image. The method is evaluated on the publicly available DRIVE and STARE databases, frequently used for this purpose and also on a new public retinal vessel reference dataset CHASE_DB1?which is a subset of retinal images of multiethnic children from the Child Heart and Health Study in England (CHASE) dataset. The performance of the ensemble system is evaluated in detail and the incurred accuracy, speed, robustness, and simplicity make the algorithm a suitable tool for automated retinal image analysis.     

Object detection with feature stability over scale space

This paper proposes a novel segmentation method based on the scale space techniques endowed with a feature stability approach. The novelty of the paper is the lifetime of the space-scale blobs measured not only by their presence and disappearance but by the stability of the features characterizing the objects of interest as well. Our numerical experiments show that the algorithm outperforms the conventional space scale algorithm applied to variable size and variable shape objects. The proposed algorithm can be used as a preprocessing step in object or pattern recognition applications to produce seeds for more accurate image segmentation methods such as the snakes or the level set techniques.     

Hydrothermal carbonization of unwanted biomass materials: Effect of process temperature and retention time on hydrochar and liquid fraction

Hydrothermal carbonization (HTC) was applied to examine the feasibility in converting coconut husk (CH) and rice husk (RH) to renewable fuel resource and valuable dissolved organic chemicals. HTC was conducted with varying process temperature (140–200 °C) and retention time (1–4 h). CH was a better feedstock to produce hydrochar as solid fuel than RH because of its compositions was significantly different. An increase in process temperature from 140 to 200 °C resulted in a decrease in hydrochar yield of CH from 77.1 to 67.8%, and corresponding decreases in O/C and H/C from 0.6 and 1.4 to 0.4 and 1.2, respectively, and this was associated to dehydration and decarboxylation reactions. Fuel ratio and HHV were in the range of 0.66–0.86 and 20.7–23.9 MJ/kg, respectively. Liquid fractions (LF) from both RH and CH were found to be abundant in dissolved organic chemicals which were regarded as valuable intermediate chemicals, including furfural, furfuryl alcohol, hydroxymethylfurfural (HMF), and low molecular-weight carboxylic acids (lactic acid, formic acid, acetic acid, levulinic acid, and propionic acid).     

Characterization of precursors to trihalomethanes formation in Bangkok source water

Resin adsorption techniques using three types of resin (DAX-8, AG-MP-50, and WA-10) were employed to characterize the raw water (RW) from the major 3 million m³/day (793 million gal/day) drinking water treatment plant in Bangkok, Thailand. The dissolved organic carbon (DOC) mass distribution sequences of the six organic fractions in raw water, from high to low, were hydrophilic neutral (HPIN), hydrophobic acid (HPOA), hydrophilic acid (HPIA), hydrophobic neutral (HPON), hydrophilic base (HPIB), and hydrophobic base (HPOB). HPIN and HPOA were the two main precursors for trihalomethanes formation (THMFP) in this water source following chlorination. The chlorination of HPON and HPIN fractions only led to the formation of mostly chloroform, while other organic fractions formed both chloroform and bromodichloromethane. The linear dependency between each organic fraction concentration and THMFP indicated that the reactions of each organic fraction with chlorine were first-order.     

Characteristics of hydrochar and liquid fraction from hydrothermal carbonization of cassava rhizome

Hydrothermal carbonization (HTC) of cassava rhizome (CR) was performed to investigate the effect of process parameters including temperature, time, and biomass to water ratio (BTW) on characteristics of hydrochar and liquid fraction products. The effect of temperature was two-fold. First, an increase in reaction temperature from 160 to 180 °C decreased hydrochar yield from 54 to 51%, however, a further increase of temperature from 180 to 200 °C saw an increase in the hydrochar yield to 58%. This was associated to degradation, polymerization, and condensation reactions during HTC. The hydrogen/carbon and oxygen/carbon atomic ratios decreased from 1.4 and 0.6 at 160 °C to 1.2 and 0.4 at 200 °C, respectively. The liquid fraction contained various valuable chemical species including, glucose, furan compounds, (furfural, furfuryl alcohol, hydroxymethylfurfural), volatile fatty acid (succinic acid, lactic acid, formic acid, acetic acid, levulinic acid, and propionic acid) with their highest yields (wt.% dry raw material) of 4.5, 18.5, and 24.3, respectively.     

FTIR evaluation of functional groups involved in the formation of haloacetic acids during the chlorination of raw water

This work investigated the formation potential of haloacetic acid (HAA) compounds in the raw water for the Bangkhen water treatment plant (Bangkok, Thailand). The resin adsorption technique (with three different types of resins, i.e. DAX-8, AG-MP-50 and WA-10) was employed to characterize the organic content in the raw water into six fractions, i.e. hydrophobic neutral (HPON), hydrophobic acid (HPOA), hydrophobic base (HPOB), hydrophilic neutral (HPIN), hydrophilic acid (HPIA) and hydrophilic base (HPIB). Hydrophilic species appeared to be the predominant organic species in this water source (approximately 60%) with the neutral fraction being the most abundant (approximately 40%). Hydrophobic species, on the other hand, played the most important role in the formation of haloacetic acids as they contributed to as much as approximately 56% of total HAA formation potential. Among the three hydrophobic species, the hydrophobic base exhibited the highest specific HAA formation with 208mugHAAs/mg of dissolved organic carbon (DOC). Each organic fraction was examined for its associated functional groups by Fourier transform infrared (FTIR). The investigation of the formation of HAAs was achieved by tracking the changes in the FTIR results of the same water sample before and after the chlorination reaction. Based on the results obtained from this study, carboxylic acids, ketone, amide, amino acids and aromatic characteristic organics seemed to be the main precursors to HAA formation.