In this paper, we propose a generalization of the box fractal dimension in images by considering the curve obtained from its value as a function of the binarization threshold. This curve can be used to describe speckle patterns. We show some examples of both objective simulated and experimental and subjective speckle in some cases of interest. The concept can be extended for all types of images.
Speckle is being used as a characterization tool for the analysis of the dynamics of slow-varying phenomena occurring in biological and industrial samples at the surface or near-surface regions. The retrieved data take the form of a sequence of speckle images. These images contain information about the inner dynamics of the biological or physical process taking place in the sample. Principal component analysis (PCA) is able to split the original data set into a collection of classes. These classes are related to processes showing different dynamics. In addition, statistical descriptors of speckle images are used to retrieve information on the characteristics of the sample. These statistical descriptors can be calculated in almost real time and provide a fast monitoring of the sample. On the other hand, PCA requires a longer computation time, but the results contain more information related to spatial–temporal patterns associated to the process under analysis. This contribution merges both descriptions and uses PCA as a preprocessing tool to obtain a collection of filtered images, where statistical descriptors are evaluated on each of them. The method applies to slow-varying biological and industrial processes.
Speckle is being used as a characterization tool for the analysis of the dynamic of slow varying phenomena occurring in biological and industrial samples. The retrieved data takes the form of a sequence of speckle images. The analysis of these images should reveal the inner dynamic of the biological or physical process taking place in the sample. Very recently, it has been shown that principal component analysis is able to split the original data set in a collection of classes. These classes can be related with the dynamic of the observed phenomena. At the same time, statistical descriptors of biospeckle images have been used to retrieve information on the characteristics of the sample. These statistical descriptors can be calculated in almost real time and provide a fast monitoring of the sample. On the other hand, principal component analysis requires longer computation time but the results contain more information related with spatial-temporal pattern that can be identified with physical process. This contribution merges both descriptions and uses principal component analysis as a pre-processing tool to obtain a collection of filtered images where a simpler statistical descriptor can be calculated. The method has been applied to slow-varying biological and industrial processes
We explore the performance of two algorithms to screen loci of equal activity in dynamic speckle images. Dynamic speckle images are currently applied to several applications in medicine, biology, agriculture and other disciplines. Nevertheless, no objective standard has been proposed so far to evaluate the performance of the algorithms, which must be then relied on subjective appreciations. We use two case studies of activity that do not bear the biologic inherent variability to test the methods: “Generalized Differences” and “Fujii”, looking for a standard to evaluate their performance in an objective way. As study cases, we use the drying of paint on an (assumed) unknown topography, namely the surface of a coin, and the activity due to pre heating a piece of paper that hides writings in the surface under the paper. A known object of simple topography is included in the image, besides of the painted coin, consisting in a paint pool where the depth is a linear function of its position. Both algorithms are applied to the images and the intensity profile of the results along the linear region of the pool activity is used to estimate the depth of the geometric topography hidden under paint in the coin. The accuracy of the result is used as a merit estimation of the corresponding algorithm. In the other experiment, a hidden dark bar printed on paper is covered with one or two paper leaves, slightly pre heated with a lamp and activity images registered and processed with both algorithms. The intensity profile of the activity images is used to estimate which method gives a better description of the bar edges images and their deterioration. Experimental results are shown.
The concept of spatial coherence is usually hard to be understood the first time that it is studied. We propose here a geometric description that does not contain mathematical difficulties and permits to understand how a Young´s Fringes system is obtained with a source not spatially coherent. It is based in a very simple experiment that permits the detection of spatial coherence in a scene. Experimental results are shown
Dynamic speckle laser (DLS) technique has been applied to the analysis of different biological systems, inorganic materials and industrial processes. In this paper, we use this technique to analyze the hygroscopic properties of different types of porcelain and papers for electrotechnical purposes. Experimental speckle results showed different behavior depending on physicochemical and textural properties of the samples.
We present a dynamic laser speckle method to easily discriminate filamentous fungi from motile bacteria in soft surfaces, such as agar plate. The method allows the detection and discrimination between fungi and bacteria faster than with conventional techniques. The new procedure could be straightforwardly extended to different micro-organisms, as well as applied to biological and biomedical research, infected tissues analysis, and hospital water and wastewaters studies.
In previous works we reported several speckle interferometry methods applied to analyze paint drying processes. In this
paper we present the development of a low cost optoelectronic system for monitoring the drying status of different types
of paints. The system is composed by a laser diode, a linear CCD sensor and a microcontroller.
One of the key points of the system is the algorithm that processes the speckle patterns produced by the laser beam
scattered from the paint. The temporal evolution of the speckle carries information of the paint status. The proposed
algorithm modifies one of its parameters to follow the speckle rate of change, allowing a real-time measurement of the
drying process.
The results obtained with this system are compared to the ones obtained by the method that measures the paint weight
loss in time, due to the solvent evaporation, and to the results from other methods that process the temporal evolution of
the speckle with different algorithms.
When a lesion occurs in a blood vessel, a series of mechanisms are activated to stop hemorrhage by increasing blood
viscosity at the wounded place.
If a sample of blood extracted of the human body is illuminated with coherent light, a time varying speckle pattern is
observed. It is show high activity at the start and decreases with time until it finally stop.
The analysis of these patterns shows a degree of correlation between speckle activity and the temporal evolution of the
clot.
These preliminary results are promising for the continuation of studies aiming to the application of biospeckle techniques
to the analysis of coagulation times.
Speckle techniques have been extensively employed in biomedical applications. It has been shown, that these non
invasive optical techniques are useful to discriminate healthy tissues from those presenting some type of pathology. In
this work we analyze speckle patterns from histological samples of gastric mucosa obtained by means of digestive
endoscopies with three different histopathological confirmed diagnoses: atrophy, metaplasia and dysplasia. We studied
biopsies from 27 patients and formed groups following the corresponding speckle contrast features. Three different
groups according to the speckle contrast were established: higher for intestinal metaplasia, intermediate for gastric
dysplasia and low for gastric atrophy. The comparison with histopathology shows a high value of concordance between
both tests, making this methodology emerges as a possible new classification system for qualitative and quantitative
gastric biopsy using optical techniques.
Biospeckle patterns are named also "boiling" speckles due to its dynamic appearance. This activity takes place when the
sample changes its properties due to diverse causes. This phenomenon is characteristic of biological samples and of the
some industrial process. There are many descriptors that have been developed to characterize biospeckle patterns. This
paper presents some approaches to compare and evaluate a set of time domain descriptors using a controlled experiment.
This paper proposes the design of decision models with Computational Intelligence techniques using image sequences of
dynamic laser speckle. These models aim to characterize the dynamic of the process evaluated through Temporal History
Speckle Patterns (THSP) using a set of available descriptors. The models use those sets selected to improve its
effectiveness, depending on the specific application. The techniques of computational intelligence field include using
Artificial Neural Networks, Fuzzy Granular Computation, Evolutionary Computation elements such as Genetic
Algorithms, among others. The results obtained in experiments such as the evaluation of bacterial chemotaxis, and the
estimation of the drying time of coatings are encouraging and significantly improve those obtained using a single
descriptor.
Chemotaxis has a meaningful role in several fields, such as microbial physiology, medicine and biotechnology. We present a new application of dynamic laser speckle (or biospeckle) to detect different degrees of bacterial motility during chemotactic response experiments. Encouraging results showed different bacterial dynamic responses due to differences in the hardness of the support in the swarming plates. We compare this method to a conventional technique that uses white light. Both methods showed to be analogous and, in some cases, complementary. The results suggest that biospeckle processed images can be used as an alternative method to evaluate bacterial chemotactic response and can supply additional information about the bacterial motility in different areas of the swarm plate assay that might be useful for biological analysis.
In this work we present to methods to evaluate activity in low dynamic speckle patterns. The first one is based on the
behavior analysis of the vortices associated to the pattern. The other one consists in binarizing the speckle image. The
speckle grain areas, also called islands, experiment displacements and deformations. The variations of the island features
were analyzed with the aim of finding a correlation with the activity of the speckle pattern. Both methods were evaluated
in numerical simulations and controlled experiments. From the obtained results, it was possible to conclude that the
developed methods can be very useful for the analysis of low activity speckle patterns with some advantages with other
methods.
Dynamic speckle is a useful technique to show biological tissue activity and evolving processes in industry. There are several algorithms for quantitative and qualitative characterization of dynamic speckle. We use the statistical method receiver operating characteristic (ROC) to compare some speckle algorithms. We estimate the capacity of these descriptors to discriminate different activities and the smallest number of images necessary for a correct description of the phenomena. We also use the ROC curves to estimate the best conditions required by some activities. The results are verified using an activity image.
Dynamic speckle techniques are useful tools for the study of temporal evolution. We use the difference histogram (DH) method for texture speckle image characterization. To test this proposal, two experiments were developed, concerning activity speckle images corresponding to live and dead seeds, and to drying of synthetic paints. The time history of the speckle pattern obtained from different stages of the samples was analyzed. The results are compared with those obtained from previous investigations performed with other methods. The comparison reveals that the proposed DH method is appropriate for this task.
There are several algorithms for quantitative and qualitative characterization of dynamic speckle. In this paper, the statistical method named R.O.C (Receiver Operating Characteristic) is used to compare some speckle algorithms. We estimate the capacity of these descriptors in the discrimination of different activities.
Dynamic speckle or biospeckle is a phenomenon generated by laser light scattering in biological tissues. It is also present in some industrial processes where the surfaces exhibit some kind of activity. There are several methods to characterize the dynamic speckle pattern activity. For quantitative measurements, the Inertia Moment of the co occurrence matrix of the temporal history of the speckle pattern (THSP) is usually used.
In this work we propose the use of average dimensions (AD) for quantitative classifications of textures of THSP images corresponding to different stages of the sample.
The AD method was tested in an experiment with the drying of paint, a non biological phenomenon that we usually use as dynamic speckle initial test. We have chosen this phenomenon because its activity can be followed in a relatively simple way by gravimetric measures and because its behaviour is rather predictable. Also, the AD was applied to numerically simulated THSP images and the performance was compared with other quantitative method. Experiments with biological samples are currently under development.
Dynamic speckle images are useful tools to characterize the activity of biological tissues. In this paper, this technique was applied to determine chemotaxis responses of Pseudomonas aeruginosa towards attractants. Generalized weighted differences, wavelet entropy and spectral bands decomposition algorithms were used to characterize the speckle activity. Experimental results show regions with different bacterial activity. Dynamic speckle method exhibits a good performance for this application.
When the speckle pattern produced by a scattering surface shows some type of activity, the speckle distribution changes in time. This paper presents a method to locally estimate the spatial variance of the temporal variation of the phase as an activity descriptor in a sequence of dynamic speckle. This method is based on the computation of the spatial autocorrelation of the speckle intensity using a sliding window. The image obtained from the resulting spatial variance matrix reveals areas of the sample with different speckle activity. Results obtained for both simulated and experimental data are also shown.
Dynamic speckle or biospeckle is observed in biological samples illuminated by laser light. The properties and applications of this phenomenon have been treated in the literature. In this paper, we present a method of dynamic speckle analysis based on the filtering in frequency bands of the temporary history of each pixel. Butterworth filters are applied to the temporary evolution and different images are constructed showing the energy in each frequency band. Applications on vegetable specimens examples are shown.
When an optically rough surface illuminated by a laser evolves in time the scattered light gives rise to a dynamic speckle pattern and its variation depends on the activity of the sample. Biological samples show this behavior but it also can be observed is some other dynamic processes such as drying of paint, corrosion, heat exchange, blood flow, vibrations, etc. In this work we present a dynamic speckle phenomenon that occurs in the development of foams. The experimental results show the time evolution of the samples and offer a potential applicability of this measurement technique to the assessment of this type of processes.
Algorithms used to process a speckle image are limited by the resolution of the CCD camera and the employed digitalization system. We propose the use of dithering procedures to increase the intensity discrimination and improve the contrast resolution. This technique consists in decreasing the quantification error by performing several measurements to which a random value is added in each measurement before detection. Hence, it is possible to find a more approximated value to the real one. The precision increase results from the use of multiple images to which a determined white-light intensity has been added. This work shows the results of applying dithering to improve the precision of methods that use speckle contrast. It is a frequently used quantity in the implementation of activity images and in the determination of surface roughness. Numerically simulated images were used to verify the reliability of the technique whose intensities were later quantified for processing. The observed mean squared error is lower when this technique is employed, and the level of improvement depends on the size of the used windows. A device for the experimental verification of the results is in the design stage.
The dynamic speckle is a phenomenon generated by laser light scattering in biological tissues and it is also present in some industrial processes where the surfaces exhibit some kind of activity. In this work we present preliminary results of a numerical model to describe the time history of a dynamic speckle pattern considering very simplified situations.
In this paper a soap film is characterized by using a speckle interferometer. The arrangement consists of a double-exposure specklegram obtained through a double-aperture system, by introducing a wedge in front of one aperture in one exposure. It is assumed that a uniform displacement of the diffuser is produced between exposures. The average intensity distribution and the changes experimented by the interferometric fringe visibility in the Fourier plane due to the introduction of a soap film in each exposure are analyzed.
The dynamic speckle is a phenomenon generated by laser light scattering in biological tissues and it is also present in some industrial processes where the surfaces exhibit some kind of activity. In our case, the process of drying of paint has been studied and its activity is explored using dynamic speckle techniques. Two alternative speckle contrast methods are presented to characterize faster processes.
A school optical equipment has been designed and developed. It is the result from the cooperative activities of researchers and experts in didactic of the science. The equipment includes a handbook, experimental guides and proposals to be carried in the classroom.
The dynamic speckle, also known as biospeckle or bioactivity is a phenomenon generated by laser light scattering in biological tissues or in surfaces exhibiting some kind of activity. In our case, seeds tissue has been employed and its activity studied and explored. In this research work we suggest a bio-speckle technique as a potential methodology to analyze seeds viability.
A methodology to dynamic speckle analysis by using the wavelet transform (WT) is developed. The optimal texture descriptors are determined. The time evolution of the speckle pattern is described through the behavior of the Mahalanobis distance. From the behavior of this distance function, two parameters are defined that characterize the evolution. An example devoted to the drying of paint assessment is presented.
When a rough surface changes, its optical properties change also and the scattered light shows intensity fluctuations named dynamic speckle. Fruits, even hard peel ones, shows a speckle activity that can be related to maturity, turgor, damage, aging, and mechanical properties. Many techniques have been sued to study these properties, most of them destructive ones. We present an application of dynamical speckle to the study of impact on apples and the analysis of bruises produced by them. The aim is to correlate physical properties of apples with quality factors.
An alternative image multiplexing technique is proposed. In the arrangement implemented, the input is imaged by introducing a multiple aperture pupil in the imaging lens. Then, the speckle pattern is modulated by several system of fringes. The input images are sequentially encoded by using a different pupil during each exposure. The pupil arrangements implemented are selected to concentrate in each spot the spectral information corresponding to not more than two exposures. The spectral amplitude components for a pari of exposures are added into the common diffraction spots. All the diffraction spots contain information about a pair of inputs. Then, an image binary operation can be carried out in each spot. The technique is implemented by using as recording media photographic films and photorefractive crystals. The BSO crystal as recording medium is quite adequate in the applications proposed because it permits multiple storage in real time. However, due to its volume nature, each speckle grain exhibits angular selectivity in addition to those features observed in bidimensional media.
In speckle photography the pupil aperture is usually not modified between exposures. In our work, the change of the pupil aperture scale between exposures is analyzed on the basis of double-exposed image speckle, before and after a diffuse in-plane displacement is done. The apertures have the same shape but its scale is modified between exposures. Note that the relative position of the aperture is maintained. In particular, we analyze a simple case that uses a circular aperture whose diameter is modified for recording each image. The intensity in the image plane and the fringe visibility are evaluated, in terms of the geometric characteristics of the pupils.
A cheap piezoelectrically driven mirror can be easily constructed in the laboratory. It can be located in one arm of a DSPI interferometer in order to introduce a controlled phase step. A procedure to calibrate this device is shown, that is based on the evaluation of the fringes obtained with the interferometer. To evaluate the performance of the calibrated device, the phase map of a simulated plane object is calculated, using the four-step algorithm for the images of a speckle interferogram.
This work shows a new technique as a potential methodology to analysis seed. The technology is the dynamic speckle, phenomena produced by the laser illumination on a biological tissue, in this case the seed tissues. In order to develop this technique, it was necessary to know exactly the effect of the water content in the seed on the results, that was evaluated in this research, by the evaluation of the Inertia Moment of seeds in five levels of moisture (13, 20, 30, 37 and 46%). One of the treatments was the use of pvc film to eliminate the evaporation effect. It was analyzed 450 seeds in five degrees of moisture, with and without film, at three consecutive times, and also in a three times replication. Another experiment was the comparison of dead and alive seeds activity by the Inertia Moment in time. The results showed that the moisture influence the level of activity measured by the Inertia Moment technique, that is an important condition to be controlled on the future experiments, and that it is possible to separate dead to alive seeds by Inertia Moment.
An image multiplexing method based on the internal modulation of speckle grains by employing different multiple aperture pupils for recording is proposed. The interferometric fringes profile and visibility in the Fourier plane, for uniform in-plane displacement double- exposed specklegrams through different pupils recording, are analyzed in terms of the geometric parameters of the pupils. Experimental evidences are presented.
The drying of paints was followed using the time evolution of the activity of dynamic speckle patterns. For processing the data an alternative method based in the use of the second order moment of the modified co-occurrence matrix of the time history of its intensity was used. The experimental results obtained were compared with gravimetrical techniques. The results are discussed on the basis of the knowledge of the coating drying process.
We present a display showing dynamic speckle local activity as that observe when coherent light illuminates biological samples (biospeckle). Regions differing in their activity are shown as different gray levels. Results obtained with seeds and drying of paint are shown. We propose its use in the determination of seeds viability, detection of corrosion centers and local variations in surface roughness.
The possibility of using a BSO crystal as a recording medium of specklegrams with carrying frequency fringes, to storage multiple interferograms, for uniform in-plane displacements, is presented. Experimental results are shown.
The present work demonstrates the use of a general purpose interferometer to measure the deformations of a scattering surface by processing speckle patterns instead of smooth wavefronts. The operation of the interferometer are re- programmed to include algorithms adapted to handling speckle patterns. Details of the measuring operation are described, limits of applicability are discussed, and experimental results are presented.
The modal distribution at the output of a multimode optical fiber behaves as a speckle pattern. Further, a speckle pattern carries information on the pupil diameter of the optical system exit aperture. Pupil measurements by speckle size determination may not be an easy task, because of the statistical nature of the speckle phenomena. The measurement of a multimode fiber core is proposed using a speckle autocorrelation algorithm to obtain the minimum speckle diameter present in the pattern generated by the fiber. Both computer simulations and actual pupils are used to test its performance. Core diameter measurements are carried out showing good agreement with the specifications supplied by the fiber manufacturer.
The full width at half maximum (FWHM) is sometimes used to characterize the autocorrelation function of the time history of a speckle pattern. We propose to include more autocorrelation points to diminish the variability of the measurement. The width of the equivalent rectangle (WER) and the X*LOG X measurements are defined and some simulations and experimental results obtained are shown.
3-D data display can be classified into holographic and non-holographic.
(1]. Normally, the amount of information stored in a hologram i very
large. In this way, if only deph perception is required, the stereoscopic
techniques provide an adequate 3-D display. Among the non-holographic
method, we have developed an optical method for storing on a single
recording plate different perspectives of a 3-D scene [2). In this paper
we propose such stereoscopic method for displays of moving objects.
Phaseshifting interferometry applied to speckle fields is described. Experimental cases of both weak and strong scatterers are investigated. Statistical parameters are sought on timing of the polishing process of optical sample surfaces. 1 .
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