Speckle Image Processing Research Articles

Periodic Patterns of Actin Turnover in Lamellipodia and Lamellae of Migrating Epithelial Cells Analyzed by Quantitative Fluorescent Speckle Microscopy

We measured actin turnover in lamellipodia and lamellae of migrating cells, using quantitative Fluorescent Speckle Microscopy. Lamellae disassembled at low rates from the front to the back. However, the dominant feature in their turnover was a spatially random pattern of periodic polymerization and depolymerization moving with the retrograde flow. Power spectra contained frequencies between 0.5 and 1 cycle/min. The spectra remained unchanged when applying Latrunculin A and Jasplakinolide in low doses, except that additional frequencies occurred beyond 1cycle/min. Whereas Latrunculin did not change the rate of mean disassembly, Jasplakinolide halted it completely, indicating that the steady state and the dynamics of actin turnover are differentially affected by pharmacological agents. Lamellipodia assembled in recurring bursts at the leading edge and disassembled ∼2.5μm behind. Events of polymerization correlated spatially and temporally with transient formation of Arp2/3 clusters. In lamellae, Arp2/3 accumulation and polymerization correlated only spatially, suggesting an Arp2/3-independent mechanism for filament nucleation. To acquire these data we had to enhance the resolution of quantitative Fluorescent Speckle Microscopy to the submicron level. Several algorithmic advances in speckle image processing are described enabling the analysis of kinetic and kinematic activities of polymer networks at the level of single speckles.

Mode-Shape Visualization of High-Frequency Piezoelectric Devices Using Synchronized Laser System

A full-field-view laser stroboscopic system that visualizes surface mode shapes in piezoelectric resonators has been developed. The system presented is based on stroboscopic laser irradiation, laser speckle, and two-dimensional correlation image processing. We employed a high-speed laser diode synchronized to the resonator motion to develop an in-plane vibrational distribution visualizer that is capable of operation above 10 MHz. The detection sensitivity of the proposed system is ten times better than that of previous laser speckle systems.

Kinematic manifestations of localisation phenomena in steels by digital image correlation

The aim of this paper is to show that recent advances made in the field of speckle image processing give valuable information useful in understanding and modelling of localisation phenomena. The potentialities of the proposed imaging method are illustrated by examples extracted from tensile tests performed on steel specimens. Having introduced the underlying motivations of this experimental work, this paper briefly focuses on the image processing technique and its reliability. Then, it describes the characteristics of the strain field within and outside of a propagating Lüders band. The properties of strain states associated with diffuse and localised necking are also investigated. The catalyst role of possible geometrical defects is pointed out. Finally, a method is proposed to construct, despite localisation, a local stress–strain correspondence.

Pulsed TV holography and tomography for the study of transient waves in air

Transient waves in air are recorded and reconstructed using pulsed TV holography and computerized tomography (CT). Experiments are performed with an electrical discharge between two electrodes as the acoustic wave source. The free space wave-fronts and pressure fields are reconstructed. Waves reflected and diffracted by different obstacles are also recorded and reconstructed in three dimensions. Speckle averaging and image processing techniques are used to get the high quality projection fields needed for CT reconstruction.

Processing of short sets of bright speckle images distorted by the turbulent Earth's atmosphere

We suggest and theoretically verify a new method of joint processing of bright speckle images distorted by the Earth's atmosphere. The effectiveness of this method is confirmed both by mathematical simulation and by processing of real images of a binary star.

Optical processing of speckle images with bacteriorhodopsin for pattern recognition

Logarithmic processing of images with multiplicative noise characteristics can be utilized to transform an image into one with an additive noise distribution. This simplifies subsequent image processing steps for applications such as image restoration or correlation for pattern recognition. One particularly common form of multiplicative noise is speckle, for which the logarithmic operation not only produces additive noise, but also makes it of constant variance (signal-independent). I examine the optical transmission properties of some bacteriorhodopsin films here and find them well suited to implement such a pointwise logarithmic transformation optically in a parallel fashion. I present experimental results of the optical conversion of speckle images into transformed images with additive, signal-independent noise statistics using the real-time photochromic properties of bacteriorhodopsin. I provide an example of improved correlation performance in terms of correlation peak signal-to-noise for such a transformed speckle image.

Real-time digital aperture sampling sensor

In real-time speckle imaging and speckle interferometry, there is often the need to remove a nonuniform incoherent background from the detected image to enhance the embedded coherent speckle image. Previous approaches generally require the use of a reference beam which makes the system very sensitive to mechanical instability. A new technique that operates on uncorrelated speckle images obtained by aperture sampling is proposed. The design of a real-time system for digital speckle image processing is described, and the experimental results are presented. Possible applications for the system on speckle interferometry are discussed.

Phase-gradient speckle image processing: digital implementation and noise bias terms

Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text G. J. M. Aitken, R. Houtman, and R. Johnson, "Phase-gradient speckle image processing: digital implementation and noise bias terms," Appl. Opt. 25, 1031-1031 (1986) Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article

The Simulation and Results of a New Speckle Image Processing Technique

AbstractA new technique called shift-and-add, which allows nearly diffraction-limited images to be formed of objects viewed through a randomly distorted, turbulent media, has been formulated. True images may be obtained through the earth’s atmosphere when the method is used. It has been shown that this can be achieved even though the telescope may have severe aberration and when using a much wider bandwidth than that used at present in stellar Speckle Interferometry. Results are given for an object of greater extent than simple binary or groups of point sources.