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Techniques for fast and sensitive measurements of two-dimensional birefringence distributions

APPLIED OPTICS 2003年第16期42卷 3009-3017页

作者： Shribak, M Oldenbourg, R Marine Biol Lab Woods Hole MA 02543 USA

We propose image processing algorithms for measuring two-dimensional distributions of linear birefringence using a pair of variable retarders. Several algorithms that use between two and five recorded frames allow us to optimize measurements for speed, sensitivity, and accuracy. We show images of asters, which consist of radial arrays of microtubule polymers recorded with a polarized light microscope equipped with a universal compensator. Our experimental results confirm our theoretical expectations. The lowest noise level of 0.036 nm was obtained when we used the five-frame technique and four-frame algorithm without extinction setting. The two-frame technique allows us to increase the speed of measurement with acceptable image quality. (C) 2003 Optical Society of America.

关键词： image processing algorithms image quality Imaging systems Multiple scattering Optical elements Polarized light

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A method for local deconvolution

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APPLIED OPTICS 2003年第32期42卷 6488-6494页

作者： Gureyev, TE Nesterets, YI Stevenson, AW Wilkins, SW CSIRO Mfg & Infrastruct Technol Clayton Vic 3169 Australia

A new method for deconvolution of one-dimensional and multidimensional data is suggested. The proposed algorithm is local in the sense that the deconvolved data at a given point depend only on the value of the experimental data and their derivatives at the same point. In a regularized version of the algorithm the deconvolution is constructed iteratively with the help of an approximate deconvolution operator that requires only the low-order derivatives of the data and low-order integral moments of the point-spread function. This algorithm is expected to be particularly useful in applications in which only partial knowledge of the point-spread function is available. We tested and compared the proposed method with some of the popular deconvolution algorithms using simulated data with various levels of noise. (C) 2003 Optical Society of America.

关键词： algorithms Blind deconvolution Deconvolution Fourier transforms image processing algorithms Point spread function

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Polarized light reflection from strained sinusoidal surfaces

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APPLIED OPTICS 2003年第25期42卷 5198-5208页

作者： Schulkin, B Lim, HC Guzelsu, N Jannuzzi, G Federici, JF New Jersey Inst Technol Dept Phys Univ Heights Newark NJ 07102 USA Univ Med & Dent New Jersey Sch Osteopath Med Biomech Lab Stratford NJ 08084 USA Rutgers State Univ Bioengn Program Piscataway NJ 08854 USA

We propose optical polarization imaging as a minimally invasive technique for measuring the mechanical properties of plastics and soft tissues through their change in reflectance properties with applied strain or force. We suggest that changes in surface roughness are responsible for the linear reflectivity changes with applied stretch or strain. Several aspects of this model are tested, including the dependence on the angle of incidence, the change in scattering and absorption coefficients with strain, and the lateral spatial resolution. The application of the technique to multilayer structures such as skin and competing optical effects such as laser speckle are discussed. (C) 2003 Optical Society of America.

关键词： Digital image processing image processing algorithms Multiple scattering Polarized light Strain measurement Surface roughness measurement

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Compact, broad-bandwidth fiber laser for sub-2-μm axial resolution optical coherence tomography in the 1300-nm wavelength region

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OPTICS LETTERS 2003年第9期28卷 707-709页

作者： Bizheva, K Povazay, B Hermann, B Sattmann, H Drexler, W Mei, M Holzwarth, R Hoelzenbein, T Wacheck, V Pehamberger, H Univ Vienna Christian Doppler Lab Dept Phys Med Vienna Austria MenloSyst GMBH D-82152 Martinsried Germany Univ Vienna Dept Vasc Surg Gen Hosp Vienna Vienna Austria Univ Vienna Dept Clin Pharmacol Gen Hosp Vienna Vienna Austria Univ Vienna Dept Dermatol Gen Hosp Vienna Vienna Austria

A novel, compact, user friendly fiber laser with a broad emission bandwidth (MenloSystems, lambda(c) = 1375 am, Deltalambda = 470 nm, P-out = 4 mW) was used to achieve unprecedented sub-2-mum axial resolution optical coherence tomography (OCT) in nontransparent biological tissue in the 1300-nm wavelength region. Fresh human skin and arterial biopsies were imaged ex vivo with similar to1.4-mum axial and similar to3-mum lateral resolution and 95-dB sensitivity, demonstrating the great potential for clinical OCT applications of this stable, low-cost, and turn-on-key fiber laser. (C) 2003 Optical Society of America.

关键词： Fiber lasers image processing algorithms Light sources Optical coherence tomography Optical imaging Pulsed fiber lasers

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Cartilage thickness measurements from optical coherence tomography

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS image SCIENCE AND VISION 2003年第2期20卷 357-367页

作者： Rogowska, J Bryant, CM Brezinski, ME Northeastern Univ Coll Comp Sci Boston MA 02115 USA Harvard Univ Brigham & Womens Hosp Sch Med Dept Orthoped Boston MA 02115 USA

We describe a new semiautomatic image processing method for detecting the cartilage boundaries in optical coherence tomography (OCT). In particular, we focus on rabbit cartilage since this is an important animal model for testing both chondroprotective agents and cartilage repair techniques. The novel boundary-detection system presented here consists of (1) an adaptive filtering technique for image enhancement and speckle reduction, (2) edge detection, and (3) edge linking by graph searching. The procedure requires several steps and can be automated. The quantitative measurements of cartilage thickness on OCT images correlated well. with measurements from histology. (C) 2003 Optical Society of America.

关键词： Absorption spectroscopy image processing algorithms image quality Magnetic resonance imaging Radar imaging Speckle reduction

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Tomography studies of human foreskin fibroblasts on polymer yarns

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NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 2003年 200卷 397-405页

作者： Thurner, P Müller, B Beckmann, F Weitkamp, T Rau, C Müller, R Hubbell, JA Sennhauser, U Swiss Fed Labs Mat Testing & Res CH-8900 Dubendorf Switzerland Swiss Fed Inst Technol Inst Biomed Engn CH-8044 Zurich Switzerland Univ Zurich CH-8044 Zurich Switzerland Swiss Fed Inst Technol Comp Vis Lab CH-8092 Zurich Switzerland Deutsch Elektronen Synchrotron DESY Hamburger Synchrotronstrahlungslabor HASYLAB D-22607 Hamburg Germany European Synchrotron Radiat Fac F-38043 Grenoble France

Cell culture experiments are usually performed as in vitro studies based on 2D seeding and characterization (light microscopy). With respect to the in vivo situation, however, 2D studies are often inappropriate due to the 3D character of living tissue in nature. Textiles with their versatile 3D structures are chosen as suitable scaffolds in tissue engineering for 3D in vitro studies. Micro-computed tomography using X-rays (muCT) belongs to the most promising techniques for isotropic, noninvasive 3D characterization. Using synchrotron radiation (SRmuCT) the spatial resolution can be extended to the sub-micrometer range well below cell size. muCT does not need vacuum conditions making experiments in the hydrated state possible, as we show by data from SRmuCT acquired at second and third-generation synchrotron sources. We seeded human foreskin fibroblasts on polymer multifilament yarns. These composites, embedded in a hydrogel or fluid, are held in thin-walled glass capillaries. Since the composites consist of light elements, the cells have to be labeled for visualization by the use of highly absorptive agents, osmium and gold. In order to hold the label concentration as low as possible, we present a way to choose the photon energy for which the minimum concentration is reached. Differences in threshold selection for second- and third-generation synchrotron sources are pointed out, revealing the advantages of both types with respect to quantitative analysis. The study is based on appropriate staining methods and protocols developed in our laboratory. With the results we demonstrate that SRmuCT yields images similar to established electron and light microscopy but uncovers also the microstructure in 3D space. (C) 2002 Published by Elsevier Science B.V.

关键词： computerized tomography synchrotron radiation cell complexes (geometry and topology) image processing algorithms biological physics spectroscopic- and microscopic techniques

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Tomography studies of human foreskin fibroblasts on polymer yarns

Tomography studies of human foreskin fibroblasts on polymer ...

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Spring Meeting of the European-Materials-Research-Society (E-MRS)

关键词： computerized tomography synchrotron radiation cell complexes (geometry and topology) image processing algorithms biological physics spectroscopic- and microscopic techniques

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Turbulence-induced edge image waviness: theory and experiment

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APPLIED OPTICS 2001年第9期40卷 1321-1328页

作者： Belen'kii, MS Stewart, JM Gillespie, P Georgia Inst Technol Atlanta GA 30332 USA USA Res Lab Battlefield Environm Directorate Adelphi MD 20783 USA

A theoretical model for the edge image waviness effect is developed for the ground-to-ground imaging scheme and validated by use of IR imagery data collected at the White Sands Missile Range. It is shown that angle-of-arrival (AA) angular anisoplanatism causes the phenomenon of edge image waviness and that the AA correlation scale, not the isoplanatic angle, characterizes the edge image waviness scale. The latter scale is determined by the angular size of the imager and a normalized atmospheric outer scale, and it does not depend on the strength of turbulence along the path. Spherical divergence of the light waves increases the edge waviness scale. A procedure for estimating the atmospheric and camera-noise components of the edge image motion is developed and implemented. A technique for mitigation of the edge image waviness that relies on averaging the effects of AA anisoplanatism on the image is presented and validated. The edge waviness variance is reduced by a factor of 2-3. The time history and temporal power spectrum of the edge image motion are obtained. I These data confirm that the observed edge image motion is caused by turbulence. (C) 2001 Optical Society of America.

关键词： Edge detection image processing algorithms Imaging systems Laser guide stars Machine vision Power spectra

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Structural-descriptive method for the contour processing of optical images

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JOURNAL OF OPTICAL TECHNOLOGY 2000年第7期67卷 630-633页

作者： Zinov'lev, VG AF Mozhaiskii Mil Space Engn Univ St Petersburg Russia

A structural-descriptive method is proposed for the real-time recognition of optical images of observed objects by their contours. The contours of images of objects: are described on a rectangular "raster" in the form of strings of symbols of arbitrary length in Freeman chain code. A structure metric (the Levenshtein distance) is introduced to estimate the similarity of strings. The distance between strings is determined by discrete dynamic programming. A corresponding algorithm for the processing of optical images is discussed. (C) 2000 The Optical Society of America. [S1070-9762(00)00707-7].

关键词： algorithms Distortion image processing image processing algorithms Vision

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High-speed image processing algorithms using MMX hardware

High-speed image processing algorithms using MMX hardware

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Conference on Machine Vision Applications, Architectures, and Systems Integration VI

作者： Miller, JWV Wood, J Univ. of Michigan/Dearborn (United States)

ISBN: (纸本)0819426377

Low-cost PC-based machine vision systems have become more common due to faster processing capabilities and the availability of compatible high-speed image acquisition and processing hardware. One development, which is likely to have a very favorable impact on this trend, is enhanced multimedia capabilities present in new processor chips such as Intel MMX and Cyrix M2 processors. Special instructions are provided with this type of hardware which, combined with a SIMD parallel processing architecture, provides a substantial speed improvement over more traditional processors. Eight simultaneous byte or four double-byte operations are possible. The new instructions are similar to those provided by DSP chips such as multiply and accumulate and are quite useful for linear processing operations like convolution. However, only four pixels may be processed simultaneously because of the limited dynamic range of byte data. Given the inherent limitations with respect to looping in SIMD hardware, nonlinear operations such as erosion and dilation would seem to be difficult to implement. However, special instructions are available for required operations. Benchmarks for a number of image-processing operations are provided in the paper to illustrate the advantages of the new multimedia extensions for vision applications.

关键词： machine vision image processing algorithms multimedia extensions single instruction multiple data performance gains

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