Traditionally, optical remote sensing payload design satisfies highly defined specifications arrived at by consensus of the scientific constituency. Designs are constrained by required performance such as resolution, ...
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(纸本)9780819468253
Traditionally, optical remote sensing payload design satisfies highly defined specifications arrived at by consensus of the scientific constituency. Designs are constrained by required performance such as resolution, Modulation Transfer Function (MTF), and Signal-to-Noise-Ratio (SNR). Payload designers satisfy the specification by performing hardware and cost trades. This process may lack continuous feedback between the performance of the scientific algorithms and the payload design, potentially missing optimal design points. The traditional method has produced separate and specific designs for imagery (over-sampling ratio Q > 0.8) vs. radiometry (Q < 0.8). Radiometers are scientifically precise, with highly accurate scene collection over a tightly defined pixel size exclusive of other scene points, often across several spectral channels. imagers reveal sharper features, but have considerable "bleeding" of scene radiance into adjacent pixels, causing errors in application of multispectral scientific algorithms. Recently, we created end-to-end models that optimize end scientific data products by considering the payload design and data processingalgorithms together, rather than simply satisfying a payload specification. In this process, we uncovered optimal payload design points and insights. We explore end-to-end modeling results that show an optimal single converged payload design, and data processingalgorithms that produce simultaneous radiometer and imager products. We show how payload design choices for Instantaneous Field of View (IFOV) and Ground Sampling Distance (GSD) maximize SNR for multiple data products, resulting in an optimized design that increases flexibility of space assets. This approach is beneficial as we move towards distributed and fused image systems.
We describe an innovative methodology for determining the quality of digital images. The method is based on measuring the variance of the expected entropy of a given image upon a set of predefined directions. Entropy ...
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We describe an innovative methodology for determining the quality of digital images. The method is based on measuring the variance of the expected entropy of a given image upon a set of predefined directions. Entropy can be calculated on a local basis by using a spatial/spatial-frequency distribution as an approximation for a probability density function. The generalized Renyl entropy and the normalized pseudo-Wigner distribution (PWD) have been selected for this purpose. As a consequence, a pixel-by-pixel entropy value can be calculated, and therefore entropy histograms can be generated as well. The variance of the expected entropy is measured as a function of the directionality, and it has been taken as an anisotropy indicator. For this purpose, directional selectivity can be attained by using an oriented 1-D PWD implementation. Our main purpose is to show how such an anisotropy measure can be used as a metric to assess both the fidelity and quality of images. Experimental results show that an index such as this presents some desirable features that resemble those from an ideal image quality function, constituting a suitable quality index for natural images. Namely, in-focus, noise-free natural images have shown a maximum of this metric in comparison with other degraded, blurred, or noisy versions. This result provides a way of identifying in-focus, noise-free images from other degraded versions, allowing an automatic and nonreference classification of images according to their relative quality It is also shown that the new measure is well correlated with classical reference metrics such as the peak signal-to-noise ratio. (C) 2007 Optical Society of America
Integral imaging is one of the most promising techniques for delivering three-dimensional content. Most processing tasks usually require prior knowledge of the size and positions of the elemental images that comprise ...
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Integral imaging is one of the most promising techniques for delivering three-dimensional content. Most processing tasks usually require prior knowledge of the size and positions of the elemental images that comprise an integral image. In this paper we propose an automated method for calibrating the acquisition setup, by applying a preprocessing stage to an acquired integral image. The skew angle is extracted and the size and positions of the elemental images are accurately determined. For these purposes a method is developed to automatically identify an elemental image lattice that best matches the acquired integral image. (c) 2006 Optical Society of America.
Integral imaging is one of the promising three-dimensional display techniques and has many advantages. However, one disadvantage of integral imaging is the limited image depth. The image can be displayed only around t...
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Integral imaging is one of the promising three-dimensional display techniques and has many advantages. However, one disadvantage of integral imaging is the limited image depth. The image can be displayed only around the central depth plane. We propose a depth-enhanced integral imaging using multilayered display devices. We locate transparent display devices that use liquid crystal in parallel to each other and incorporate them into an integral imaging system. As a result, the proposed method has multiple central depth planes and permits the limitation of expressible depth to be overcome. The principle of the proposed method is explained, and some experimental results are presented. (c) 2006 Optical Society of America.
This paper proposes a new autofocusing method for observing cells under a transmission illumination. The focusing method uses a quick and simple focus estimation technique termed "depth from diffraction," wh...
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This paper proposes a new autofocusing method for observing cells under a transmission illumination. The focusing method uses a quick and simple focus estimation technique termed "depth from diffraction," which is based on a diffraction pattern in a defocused image of a biological specimen. Since this method can estimate the focal position of the specimen from only a single defocused image, it can easily realize high-speed autofocusing. To demonstrate the method, it was applied to continuous focus tracking of a swimming paramecium, in combination with two-dimensional position tracking. Three-dimensional tracking of the paramecium for 70 s was successfully demonstrated. (c) 2006 Optical Society of America.
We demonstrate the validity of wavelet-based processing for recognition and classification of three-dimensional phase objects. One Fresnel digital hologram of each of the three-dimensional (3-D) phase objects to be cl...
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We demonstrate the validity of wavelet-based processing for recognition and classification of three-dimensional phase objects. One Fresnel digital hologram of each of the three-dimensional (3-D) phase objects to be classified is recorded. The electronic holograms are processed digitally to permit 3-D object information to be retrieved as two-dimensional digital complex images. We use a Mexican-hat wavelet-matched filter (WMF) to enhance the correlation peak and discriminate between the objects. The WMF performs a wavelet transform (WT) to enhance the significant features of the images and the correlation of the WT coefficients thus obtained. We compare the feasibility of a WMF-based object classifier with the matched-filter-based classifier to classify our four 3-D phase objects in a 3-D scene into TRUE or FALSE classes with minimal error. (c) 2006 Optical Society of America.
Colposcopy is a primary diagnostic method used to detect cancer and precancerous lesions of the uterine cervix. During the examination, the metaplastic and abnormal tissues exhibit different degrees of whiteness (acet...
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Colposcopy is a primary diagnostic method used to detect cancer and precancerous lesions of the uterine cervix. During the examination, the metaplastic and abnormal tissues exhibit different degrees of whiteness (acetowhitening effect) after applying a 3%-5% acetic acid solution. Colposcopists evaluate the color and density of the acetowhite tissue to assess the severity of lesions for the purpose of diagnosis, telemedicine, and annotation. However, the color and illumination of the colposcopic images vary with the light sources, the instruments and camera settings, as well as the clinical environments. This makes assessment of the color information very challenging even for an expert. In terms of developing a Computer-Aided Diagnosis (CAD) system for colposcopy, these variations affect the performance of the feature extraction algorithm for the acetowhite color. Non-uniform illumination from the light source is also an obstacle for detecting acetowhite regions, lesion margins, and anatomic features. There fore, in digital colposcopy, it is critical to map the color appearance of the images taken with different colposcopes into one standard color space with normalized illumination. This paper presents a novel image calibration technique for colposcopic images. First, a specially designed calibration unit is mounted on the colposcope to acquire daily calibration data prior to performing subject examinations. The calibration routine is fast, automated, accurate and reliable. We then use our illumination correction algorithm and a color calibration algorithm to calibrate the exam data. In this paper we describe these techniques and demonstrate their applications in clinical studies. (C) 2006 Optical Society of America.
Electron cryotomography (cryoET) has the potential to elucidate the structure of complex biological specimens at molecular resolution but technical and computational improvements are still needed. This work addresses ...
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Electron cryotomography (cryoET) has the potential to elucidate the structure of complex biological specimens at molecular resolution but technical and computational improvements are still needed. This work addresses the determination and correction of the contrast transfer function (CTF) of the electron microscope in cryoET. Our approach to CTF detection and defocus determination depends on strip-based periodogram averaging, extended throughout the tilt series to overcome the low contrast conditions found in cryoET. A method for CTF correction that deals with the defocus gradient in images of tilted specimens is also proposed. These approaches to CTF determination and correction have been applied here to several examples of cryoET of pleomorphic specimens and of single particles. CTF correction is essential for improving the resolution, particularly in those studies that combine cryoET with single particle averaging techniques. (c) 2006 Elsevier B.V. All rights reserved.
Dynamic speckle illumination (DSI) microscopy is a widefield fluorescence imaging technique that provides depth discrimination. The technique relies on the illumination of a sample with a sequence of speckle patterns....
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Dynamic speckle illumination (DSI) microscopy is a widefield fluorescence imaging technique that provides depth discrimination. The technique relies on the illumination of a sample with a sequence of speckle patterns. We consider an imageprocessing algorithm based on a differential intensity variance between consecutive images, and demonstrate that DSI sectioning strength depends on the dynamics of the speckle pattern. Translated speckle patterns confer greater sectioning strength than randomized speckle patterns because they retain out-of-focus correlations that lead to better background rejection. We present a theory valid for arbitrary point-spread-functions, which we corroborate with experimental results. (c) 2006 Optical Society of America
A novel optical edge projection method for surface contouring of an object with low reflectivity is presented. A structured light edge is projected onto a dark surface, and the image is captured by a CCD camera. The s...
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A novel optical edge projection method for surface contouring of an object with low reflectivity is presented. A structured light edge is projected onto a dark surface, and the image is captured by a CCD camera. The surface profile of the object is then evaluated by an active triangular projection technique, and a whole-field three-dimensional contour of the object is obtained by scanning the optical edge over the entire object surface. An edge detection method based on a continuous wavelet transform (CWT) is employed to determine the location of the optical edge. The method of optical edge detection is described, and characteristic details of gray-level distribution along the edge are analyzed. It is shown that the proposed wavelet edge detection method is not dependent on any threshold values;hence the true edge position can be determined without subjective selection. A black low-reflectivity object surface made from woven carbon fiber is measured, and the experimental results show that the profile of a woven carbon fiber can be obtained by the proposed method. (C) 2006 Optical Society of America.
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