Digital Image Analysis Techniques Research Articles

Automated bullet-identification system based on surface topography techniques

Every firearm has individual characteristics that are as unique to it as fingerprints are to human beings. When a firearm is fired, it transfers these characteristics – in the form of microscopic scratches and dents – to the fired bullets and cartridge casings. The rifling of the barrel of the firearm marks the bullets travelling through it, and the firearm's breech mechanism marks the ammunition's cartridge casing. Characterising these marks is the critical element in identifying firearms. Traditionally the comparison of ballistic evidence has been a tedious and time-consuming process requiring highly skilled examiners. In the past decade, engineers have created automated ballistics identification systems that meld traditional comparison microscopes with digital cameras, computers, huge databases, and image analysis techniques. This kind of system can help investigators to link crimes by automatically finding similarities among images of bullet but suffering significant drawbacks and minimal matching. More recently, approaches based on 3D digital representations of evidence surface topography have started to appear, both in research and industrial products. Potentially the introduction of 3D surface topography measurement can overcome the limitations of digital imaging systems by making the bullet surface measurement reproducible and reliable. A 3D quantitative approach for bullet identification is proposed in this paper. In this system the surface topography of the whole bullet can be acquired for analysis and identification. Primary researches have been done by applying advanced surface topography techniques for bullet marks’ characteristics extraction. A variety of 2D and 3D visualization graphics have also been provided to help firearm examiners to make final decisions.

Diagnosis of cotton N status using digital image analysis technique

Diagnosis of cotton N status using digital image analysis technique

Diagnosis of cotton N status using digital image analysis technique

This paper is an investigation of the possibility of N nutrition diagnosis in cotton plant,using digital image analysis of digital camera shots,and researches into the relationships between spectral and biology parameters,which could denote cotton N status.The results show a significant linear correlation between feature spectral parameters and total N concentration in cotton plant.The same holds true for the relationship of cotton leaf N concentration.The best relationship between spectral parameters and total N concentration occurs during full-budding stage.However,at full-flowering stage,regression coefficient between spectral parameters and cotton leaf N concentration is the best.G/(G+R+B)parameter can be considered an important indictor of N status diagnosis.Results of the experiment show that ground-canopy coverage percent and LAI,biomass and accumulation of absorbed N,significantly correlate for the entire cotton growth stage.From sprouting to full-flowering,the correlation hits a high level of significance(P0.01).At last the test results indicate that ground-canopy coverage percent has a better estimation precision for LAI,biomass and accumulated absorbed N,and with a relative error percent of 26.2%,3.46% and 3.37%,respectively.

A Direct Approach for Quantifying Stream Shading

Management and regulatory standards for stream shading have been established to mitigate excessive stream temperature. Existing shade assessment tools, however, are inadequate for monitoring extensive stream networks. Our objectives were to develop and evaluate an efficient, low-cost field technique for sampling stream-surface shading using digital images and to evaluate the efficiencies and effectiveness of eight different digital image analysis techniques for shade assessments. We developed a quadrat-based technique and associated field equipment to directly photograph stream-surface shading. Sampling at random points (pixels) within the resultant digital images was the most accurate, efficient, and robust image analysis technique. An approach pairing the photographic field technique and the random point-sampling image analysis technique should enable managers to conduct ground-based assessments of stream shading over extensive stream networks. This approach may also provide an efficient means of collecting ground truth samples for even broader scale, remote sensing–based stream-shade assessments. Estándares para el manejo y regulación de sombras sobre corrientes de agua han sido establecidos para mitigar las temperaturas excesivas en las mismas. Las herramientas existentes para la evaluación de sombras son, sin embargo inadecuadas para el monitoreo extensivo de las redes de drenaje. Nuestros objetivos fueron desarrollar y evaluar una técnica de campo eficiente y de bajo costo para muestrear la sombra sobre la superficie de las corrientes de agua usando imágenes digitales, y evaluar las eficacias y eficiencias de ocho diferentes técnicas de análisis de imágenes digitales para las evaluaciones de sombra. Hemos desarrollado una técnica basada en cuadrantes y asociada al equipo de campo para fotografiar directamente la sombra en la superficie de la corriente de agua. Un muestreo de puntos al azar (pixeles) dentro de las imágenes digitales resultantes fue la técnica de análisis de imagen más precisa, eficiente, y robusta. Una estrategia combinando la técnica fotográfica de campo y la técnica robusta de muestreo de puntos al azar con imagines digitales podría permitir a los usuarios llevar a cabo evaluaciones de campo extensivas de las sombras existentes sobre las corrientes de agua. Esta estrategia podría también proporcionar medios eficientes para recolectar muestras de campo incluso para evaluaciones de sombra a escalas más amplias usando metodologías basadas en sensores remotos.

Digital image analysis of EUS images accurately differentiates pancreatic cancer from chronic pancreatitis and normal tissue

Concomitant changes of chronic pancreatitis markedly degrade the performance of EUS in diagnosing pancreatic adenocarcinoma (PC). Digital image analysis (DIA) of the spatial distribution of pixels in a US image has been used as an effective approach to tissue characterization. We applied the techniques of DIA to EUS images of the pancreas to develop a classification model capable of differentiating pancreatic adenocarcinoma from non-neoplastic tissue. Representative regions of interest were digitally selected in EUS images of 3 groups of patients with normal pancreas (group I), chronic pancreatitis (group II), and pancreatic adenocarcinoma (group III). Texture analyses were then performed by using image analysis software. Principal component analysis (PCA) was used for data reduction, and, later, a neural-network-based predictive model was built, trained, and validated. Tertiary academic medical center. Patients undergoing EUS of the pancreas. A total of 110, 99, and 110 regions of interest in groups I, II, III, respectively, were available for analysis. For each region, a total of 256 statistical parameters were extracted. Eleven parameters were subsequently retained by PCA. A neural network model was built, trained by using these parameters as input variables for prediction of PC, and then validated in the remainder of the data set. This model was very accurate in classifying PC with an area under the receiver operating characteristic curve of 0.93. Exploratory study with a small number of patients. DIA of EUS images is accurate in differentiating PC from chronic inflammation and normal tissue. With the potential availability of real-time application, DIA can develop into a useful clinical diagnostic tool in pancreatic diseases and in certain situations may obviate EUS-guided FNA.

Rock-type classification of an iron ore deposit using digital image analysis technique

In this paper, the rock types of an iron ore deposit were classified using the digital image analysis technique. The image acquisition and analysis of blasted rocks were conducted in a laboratory for six different rock types. A total of 189 features were extracted from the individual rock samples using best-suited segmentation technique selected by validation study. The neural network technique was applied for rock classification model using image features. Five principal components, which accounts for 95% of total data variance, were selected as input parameters for the model. The misclassification error of the model for testing data was 2.4%.

Statistical Analyses of Pattern Variation in the Copper-bellied (Nerodia Erythrogaster Neglecta) and Yellow-bellied (N. E. Flavigaster) Watersnake Subspecies

We conducted a statistical evaluation of the pattern characteristics used to distinguish juvenile and adult copper-bellied (Nerodia erythrogaster neglecta) and yellow-bellied (Nerodia erythrogaster flavigaster) watersnakes. A total of 405 preserved museum specimens (juvenile = 242; adult = 163) was grouped as either neglecta, flavigaster or intermediate based on previous evaluations of the geographical variations of pattern seen in these taxa. Depending on the nature of the character, its state was either scored across its phenotypic range or measured using digital image analysis techniques. The juvenile neglecta and flavigaster phenotypes are consistent with their historical descriptions and the intermediate phenotype is nearly identical to neglecta. The amount and intensity of the dorsal pigment invasion of the ventral scales was the most informative adult charter. Digital image analyses of these characters are consistent with their historical descriptions for the neglecta and flavigaster phenotypes. For the intermediate phenotype, the amount of invading pigment was consistent with the neglecta phenotype, whereas the intensity was consistent with the flavigaster phenotype. The results of this research may provide a more objective means of identifying populations of the Federally threatened N. e. neglecta.

Centrifuge model tests on geotextile-reinforced slopes

This paper addresses the static response of geotextile-reinforced slopes resting on a firm foundation to the self-weight loading imposed in a geotechnical centrifuge at pre-failure and at failure. A series of centrifuge tests were carried out on model geotextile-reinforced sand slopes with different types of reinforcement, spacing and slope inclination. A wrap-around technique was used to represent a flexible facing. In order to initiate failure in the reinforcement layers, the ratio of the length of the reinforcement to the height of the slope was maintained as 0.85. Reinforced slope models were subjected to varied g-levels (in steps of 5g from 10g onwards) up to a maximum target g-level of 75g or to collapse, whichever occurred first. A digital image analysis technique was employed to arrive at displacement vectors of markers glued to the reinforcement layers. The displacements were used to compute and analyse the strain distribution along the reinforcement layers, and to identify the peak strain distribution pre-failure and at failure. The development of a particular type of failure mechanism was found to depend upon the tensile strength-strain characteristics of a reinforcement layer. Maximum peak strain in the reinforcement layers was observed to occur at mid-height of the slope. With an increase in slope inclination from 2V:1H to 5V:1H, the magnitude of maximum peak strain was observed to increase, and its location was observed to move downwards from mid-height of the slope. Stability analysis of the reinforced slope models was found to be in good agreement with physically observed centrifuge test results.

Analysis of the bubbling behaviour of 2D gas solid fluidized beds

Bubble characteristics are very important in the design of fluidized beds because they govern hydrodynamics and efficiency of the operation for which the bed is used. In this work, a digital image analysis technique has been developed to study the fluidization dynamics of a lab-scale two-dimensional bubbling bed. Digital image analysis may supply a great quantity of information; it is non-intrusive, capable of securing several properties simultaneously and cost effective. The image analysis method here developed allows for the simultaneous measurements of various significant bubble properties, i.e. bubble size and bubble velocity distributions, bed height and bubble-phase hold-up, by means of a purposely in-house developed software. Present results were compared with relevant literature correlations and resulted in sound agreement, thus confirming the large potential of the technique here developed.

Influence of Geogrid Layer on the Integrity of Compacted Clay Liners of Landfills

The objective of this paper is to examine the influence of geogrid layer on the integrity of clay liners of landfills. A series of centrifuge model tests were performed on model clay liners subjected to non-uniform settlements with and without a geogrid layer embedded within the top one-third portion of the clay liner moist-compacted on the wet side of its optimum moisture content at 40 g. The model clay liner material has been selected in such a way that it envelopes the material characteristics of the clay liners, which are used for constructing an impermeable barrier in a lining system. By maintaining type and location of the geogrid within the clay liner as constant, the thickness of clay liner is varied to check the possibility of reducing the thickness of a geogrid reinforced clay liner. Digital image analysis technique was employed to ascertain the initiation of cracking and to compute strains both on the surface and along the cross-section of the clay liner with and without any geogrid layer. It was observed that clay liners compacted at moulding water content towards wet side of their OMC found to experience multiple cracking at the onset of non-uniform settlements. Contrary to this, geogrid reinforced clay liner was observed to sustain large distortions and experience only tiny cracks limited up to a location of a geogrid. With an increase in thickness of the clay liner reinforced with a geogrid, geogrid reinforced compacted clay liner was observed to retain its integrity and restrains cracking completely.

Monitoring cross-border trails using airborne digital multispectral imagery and interactive image analysis techniques

The objective of this study was to evaluate image-based procedures for monitoring cross-border foot trails in the US – Mexico border zone in eastern San Diego County using airborne remote sensing techniques. Specifically, digital multi-spectral and multi-temporal imagery from an airborne digital multi-spectral imaging system, digital image processing, and visual image analysis techniques were explored in the context of detecting and delineating new trail features and updating trail GIS layers. Three trail updating approaches: map-to-image (M-I) overlay, map and image-to-image (M/I-I) differencing, map and image-to-image (M/I-I) swiping and two types of spectral transform, PCA and NDVI, were tested and compared. The M-I overlay was found to be the most reliable trail updating approach. The optimal image enhancement method for the M-I overlay approach varied with vegetation structure. PCA imagery yielded better results than NDVI imagery in a highly disturbed area and NDVI imagery performed better in a densely vegetated area. The M/I-I swiping approach was useful for distinguishing misregistered extant trails from new trail features.

Evaporation of Water Droplets on Polymer Surfaces

The evaporation of water droplets on polymer surfaces was investigated by using a digital image analysis technique. There were three distinct stages in the water evaporation process: a constant contact area mode, a constant contact angle mode, and a mixed mode that is independent of both the initial quantity of water droplets and the hydrophobic properties of the polymer surfaces. The physical factors influencing the first and second transitions in the evaporation process were found to be the attainment of the receding angle on the polymer surfaces and the Marangoni instability in the evaporating water droplets, which result from the concentration gradient of contaminants. This study also provides qualitative information about the microfluid flows inside the evaporating water droplets and the morphology of drying stains on polymer surfaces. The contaminants were found to be concentrated at the perimeter of the stains, in agreement with the observed outward microfluid flow in the mixed mode of the evaporation process.

Multiscale image analysis of microcellular solids: application to hybrid silica xerogels

A general methodology is proposed to characterize microcellular solids, the structure of which consists of a three-dimensional network of filamentary structures. The analysis is based on transmission electron microscopy observation of the filaments individually and of their spatial arrangement. The micrographs are analyzed with grey-tone digital image analysis techniques, such as opening granulometry and correlation analysis. The methodology is applied to hybrid organic-inorganic low-density silica solids synthesized by the sol-gel method with an organically modified co-reactant. The quantitative impact of the co-reactant on each structural level of the structure is assessed quantitatively.

Wing Color Predicts Future Mating Success in Male Monarch Butterflies

Predictors of male monarch butterfly mating success have eluded researchers for years. Although it has long been known that there is variation in male mating success in this species, the source of this variation remains unclear. We used digital image analysis techniques to measure fine-scale variation in three components of the orange color (hue, saturation and brightness of the orange) of the forewings of 174 males at a level of detail that has not been possible until recently, and we compared this information to the mating success of the males in captivity. A second experiment involved addition of orange coloration to the wings of 93 males before mating trials. Our results indicate that one component of the orange color (saturation) correlated with mating success in our first experiment. Furthermore, wing color manipulations had no effect, but the original saturation values of the males in the second experiment were directly related to mating success. Our results provide the first evidence that wing color in monarch butterflies relates to mating success, and they serve as an important starting point for future research.

Strain Localization in Solid Cylindrical Clay Specimens Using Digital Image Analysis (DIA) Technique

The strain non-uniformity due to the end restraint for a deforming specimen during triaxial testing of clay specimens was minimized in this study using lubricated end platens. This research presents the evidence of the occurrence of strain localization due to shear banding within the clay specimen by using DIA (Digital Image Analysis) technique. The variation in strain localization patterns of soil specimen is also studied for evaluating the influence of confining stress, loading conditions, stress history, drainage conditions, and soil's microfabric (geometric arrangement of clay platelets) by performing a series of lubricated-end triaxial tests on solid cylindrical specimens of Kaolin clay. This paper presents a comparative study based on the observed orientation of shear band formation, and the intensity of strain localization (by estimating the maximum local strain) within the specimen during its shear deformation process.

Segmental Malalignment With the Bryan Cervical Disc Prosthesis—Does it Occur?

The early clinical results with the Bryan Cervical Disc prosthesis are encouraging but 2 recent small published series have noted postoperative radiologic kyphosis of the functional spinal unit (FSU) of 4 and 6 degrees. The current study was undertaken to accurately assess the extent of any sagittal deformity after the use of this prosthesis in a substantial, multisurgeon case series. The neutral, erect x-rays of 67 consecutive patients (88 disc levels) operated by one of 3 surgeons, were examined using manual and digital image analysis techniques for FSU sagittal angulation (lordosis), prosthesis shell angulation, segmental olisthesis, and overall cervical alignment. Measurement accuracy was confirmed using interobserver and intraobserver studies. There was a median loss of 2 degrees in FSU lordosis when compared with preoperative imaging (P<0.0001, range: 8-degree loss to 5-degree gain). A median 2 degrees of prosthesis shell kyphosis also occurred (range: 15-degree kyphosis to 12-degree lordosis) but shell angulation correlated weakly with the change in FSU lordosis (rs=0.37, P=0.001). There was a significant difference in the median loss of FSU lordosis between surgeon 1 and surgeons 2 and 3 (3.5 degrees vs. 2 degrees, P=0.005). Median olisthesis of the prosthesis shells was -0.1 mm (range: +1.5 to -2.5 mm). Median postoperative overall cervical lordosis reduced by 4 degrees (P<0.004). A small loss in median FSU lordosis was observed after insertion of the Bryan disc. The observed changes were generally small but varied among both the patients and the surgeons, suggesting that variables may exist which contribute to postoperative sagittal alignment. These are the subject of an accompanying study.

INFLUENCE OF LOG TEMPERATURE IN IRREGULARITIES ON STRAND GEOMETRY DETECTED BY DIGITAL IMAGE ANALYSIS

Oriented Strand Board (OSB) wood strands, while often idealized as being rectangular and slender objects, are in fact typically very complex in shape. This complexity is important to the manufacture and performance of OSB as it influences forming, screening, blending, formation and ultimately performance of the panel. In a mill setting, strand geometry is defined by average length, width and thickness values as determined through simple caliper measurements and/or screen analyses (Gilson). The application of CCD cameras and digital image analysis techniques to rapidly acquire and analyze complex strand geometry will allow the processing of large amounts of data, thereby creating the potential for statistical process control applications. Aspen (Populus grandidentata) strands were produced from logs subjected to -6oC (20F), 21oC (70F) and 60oC (140F). Grey scale digital images of individual strands were acquired using a CCD camera (1296 x 1016 pixels) under direct lighting. The complexity of strand geometry was characterized by a variety of automated measuring procedures. As a result of this research the feasibility of applying this methodology to study geometrical distributions in strands was established. Area, length and width presented changes in their distributions due to the effect of log temperature. It was found that the irregularity ratio of strands was variable and strongly influenced by log temperature at time of stranding as well as other geometries. Statistical correlation between strands irregularity and log temperature was found (p-value<0.001).

Non-destructive evaluation of in vitro-stored plants: A comparison of visual and image analysis

In vitro plants, in slow-growth storage require routine evaluation for assessment of viability and need for repropagation. Determination of plantlet health by visual assessment is subjective and varies by genus due to variations in growth pattern and plant structure. Developing a standardized plant evaluation system would improve the efficiency of in vitro storage. This study was initiated to develop digital image analysis techniques for plantlets during slow-growth cold storage and to compare that system with visual examinations. Pear (Pyrus communis L) cultivars were chosen for this initial trial because they have an open structure and clear internode position for image composition. Pear shoots stored at 4°C in tissue culture bags were evaluated monthly by standard visual examination and by digital image analysis. Digital images were evaluated for red, green, blue, modified normalized differences of vegetation index (MNDVI), green/red ratio (G/R), intensity, hue, and saturation at the first two nodes of each, plantlet. At 6 mo., the visual ratings had declined steadily for P. communis ‘Luscious’ and ‘Bartlett—Swiss’, while ‘Belle Lucrative’ and ‘Louse Bonne de Jersey’ ratings did not show significant declines until 9 mo. Correlations between visual ratings and G/R and MNDVI values were significant (r2>=0.5) for all cultivars. Regression analysis indicated that the MNDVI and G/R ratios changed significantly over the 15-mo. rating period for most cultivars. Intensity, hue and saturation values were not consistently significant and did not correlate with visual ratings. These results will assist in the development of digital imaging as an alternative technique for evaluation of stored in vitro plantlets.

Effect of process parameters on porosity distributions in high-pressure die-cast AM50 Mg-alloy

High-pressure die-casting is the preferred manufacturing process for cast Mg-alloy components used for numerous applications. High-pressure die-cast components usually contain micro-porosity that adversely affects their mechanical properties. In this contribution, the effects of three important process parameters, gate velocity, intensification pressure, and melt temperature on the micro-porosity distributions in high-pressure die-cast AM50 Mg-alloy are quantitatively characterized. The amounts of total porosity, gas porosity, shrinkage porosity, and pore size distributions are experimentally measured using novel digital image analysis techniques that permit quantification of both gas and shrinkage pores in an unbiased manner. The experimental data lead to the following conclusions: (1) Application of intensification pressure significantly reduces the total amount of porosity primarily via reduction in the gas porosity. The intensification pressure significantly reduces the number density and area fraction of the gas pores larger than 100 μm diameter. (2) A decrease in the gate velocity decreases the total amount of porosity predominantly via a decrease in the gas porosity and a small extent of decrease in the shrinkage porosity. The lower gate velocity uniformly decreases the number density and area fraction of gas pores of all sizes (small and large). (3) A decrease in the melt temperature also reduces the total amount of porosity primarily via reduction in the gas porosity. The lower melt temperature reduces the number density and area fraction of the gas pores larger than 30 μm.

A digital image analysis technique for quantitative characterisation of high-speed sprays

A digital image analysis technique developed as a particle or droplet sizing tool and capable of measuring non-spherical objects has been examined in terms of its suitability for quantitative measurements in moderately dense sprays and in particular the potential capability for the characterisation of small diameter, high-speed two-phase flows by employing high-intensity pulsed lasers for illumination. In order to evaluate robustness of the image analysis technique (PDIA), measurement certainty and also to assess whether measurement performance is sensitive to the optical set-up, the technique was applied to data obtained from a hollow cone spray via two independent optical configurations which employed firstly a diode laser and secondly an Nd:YAG laser. The calibration response of the two optical set-ups revealed significant differences in terms of the depth-of-field characteristics and thus effective measurement volume dimensions. Despite these differences, a comparison of PDIA spray data revealed excellent agreement between the two datasets for measured diameters in the range 10–90 μm in the number distributions which not only confirmed robustness of the technique but also the potential of PDIA for the measurement of fast, small diameter objects. Subsequent comparisons of the PDIA data were made with PDA data obtained within the same spray in space and time and showed excellent agreement between the two techniques for droplets larger than approximately 25 μm in diameter. Discrepancies between PDIA and PDA were observed in the volume size distributions for the larger droplets measured whose diameters were greater than approximately 40 μm. This discrepancy is due to the ability of PDIA to measure the diameter of non-spherical droplets which were shown to exist in significant numbers at this measurement location within the spray. In contrast, the well-established technique PDA, which relies on the assumption of droplet sphericity clearly does not detect the presence of these larger deformed droplets.