We presented a set of physics motivated features for classifying photographic and computer graphic images in our previous work [1]. We also deployed an online demo system for distinguishing photographic and computer g...
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ISBN:
(纸本)9781424412259
We presented a set of physics motivated features for classifying photographic and computer graphic images in our previous work [1]. We also deployed an online demo system for distinguishing photographic and computer graphic images in October 2005 [21, which features our geometry classifier, together with the wavelet classifier, and the cartoon classifier. On the first anniversary of its launch, we have received 1582 submitted images, through which we perform an analysis on the user behavior, the image set characteristics, and the classifier performance. We observe that online users do not provide clear judgments for about 80% of the submitted images, confirming the challenge in distinguishing photo-realistic computer graphics images from natural photographs. We also found the accuracy of our classifiers over the online submission set is consistent with that computed over an offline data set. Finally, in order to improve the online computational speed of our classifier, we perform feature selection and reduction, cutting the response time from 152 seconds to 24 seconds per image, while keeping the accuracy almost unchanged.
This paper presents a new randomized algorithm for quickly finding approximate nearest neighbor matches between image patches. Our algorithm offers substantial performance improvements over the previous state of the a...
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This paper presents a new randomized algorithm for quickly finding approximate nearest neighbor matches between image patches. Our algorithm offers substantial performance improvements over the previous state of the art (20-100x), enabling its use in new interactive image editing tools, computer vision, and video applications. Previously, the cost of computing such matches for an entire image had eluded efforts to provide interactive performance. The key insight driving our algorithm is that the elements of our search domain-patches of image pixels-are correlated, and thus the search strategy takes advantage of these statistics. Our algorithm uses two principles: first, that good patch matches can be found via random sampling, and second, that natural coherence in the imagery allows us to propagate such matches quickly to surrounding areas. Our simple algorithm allows finding a single nearest neighbor match across translations only, whereas our general algorithm additionally allows matching of k-nearest neighbors, across all rotations and scales, and matching arbitrary descriptors. This one simple algorithm forms the basis for a variety of applications including image retargeting, completion, reshuffling, object detection, digital forgery detection, and video summarization.
Texturing an animated fluid is a useful way to augment the visual complexity of pictures without increasing the simulation time. But texturing flowing fluids is a complex issue, as it creates conflicting requirements:...
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Texturing an animated fluid is a useful way to augment the visual complexity of pictures without increasing the simulation time. But texturing flowing fluids is a complex issue, as it creates conflicting requirements: we want to keep the key texture properties (features, spectrum) while advecting the texture with the underlying flow-which distorts it. In this paper, we present a new, Lagrangian, method for advecting textures: the advected texture is computed only locally and follows the velocity field at each pixel. The texture retains its local properties, including its Fourier spectrum, even though it is accurately advected. Due to its Lagrangian nature, our algorithm can perform on very large, potentially infinite scenes in real time. Our experiments show that it is well suited for a wide range of input textures, including, but not limited to, noise textures.
In this paper, we show that optical inverse tone-mapping (OITM) in light microscopy can improve the visibility of specimens, both when observed directly through the oculars and when imaged with a camera. In contrast t...
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In this paper, we show that optical inverse tone-mapping (OITM) in light microscopy can improve the visibility of specimens, both when observed directly through the oculars and when imaged with a camera. In contrast to previous microscopy techniques, we premodulate the illumination based on the local modulation properties of the specimen itself. We explain how the modulation of uniform white light by a specimen can be estimated in real time, even though the specimen is continuously but not uniformly illuminated. This information is processed and back-projected constantly, allowing the illumination to be adjusted on the fly if the specimen is moved or the focus or magnification of the microscope is changed. The contrast of the specimen's optical image can be enhanced, and high-intensity highlights can be suppressed. A formal pilot study with users indicates that this optimizes the visibility of spatial structures when observed through the oculars. We also demonstrate that the signal-to-noise (S/N) ratio in digital images of the specimen is higher if captured under an optimized rather than a uniform illumination. In contrast to advanced scanning techniques that maximize the S/N ratio using multiple measurements, our approach is fast because it requires only two images. This can improve image analysis in digital microscopy applications with real-time capturing requirements.
Any sufficiently smooth, positive, real-valued function psi : S-2 -> IR+ on a sphere S-2 can be expanded by a Laplace expansion into a sum of spherical harmonics. Given the Laplace expansion coefficients, we provid...
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Any sufficiently smooth, positive, real-valued function psi : S-2 -> IR+ on a sphere S-2 can be expanded by a Laplace expansion into a sum of spherical harmonics. Given the Laplace expansion coefficients, we provide a CPU and GPU-based algorithm that renders the radial graph of psi in a fast and efficient way by ray-casting the glyph of psi in the fragment shader of a GPU. The proposed rendering algorithm has proven highly useful in the visualization of high angular resolution diffusion imaging (HARDI) data. Our implementation of the rendering algorithm can display simultaneously thousands of glyphs depicting the local diffusivity of water. The rendering is fast enough to allow for interactive manipulation of large HARDI data sets.
Researchers have studied brain injury in children by assessing linear and angular accelerations, without taking into account vibratory loads. A proposed approach employs a new mathematical head model that includes vib...
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Researchers have studied brain injury in children by assessing linear and angular accelerations, without taking into account vibratory loads. A proposed approach employs a new mathematical head model that includes vibration to analyze how shaken-baby syndrome affects babies. To account for vibrations, it applies the finite-element method to model the stresses, strains, and displacements in the neck vertebrae and brain. This research also modeled the effects of a single blow to the head. In both cases, researchers determined the extent of alterations by comparing brain tissue strength with predictions of increased tension. The vibration results predict alterations in the cervical vertebrae in some oscillation modes and are consistent with studies of cervical cord whiplash injuries. The single-blow results predict brain and spinal cord alterations and are consistent with scanner slices made by other researchers. [ABSTRACT FROM PUBLISHER]
Supercomputing centers are unique resources that aim to enable scientific knowledge discovery by employing large computational resources-the 'Big Iron.' Design, acquisition, installation, and management of the...
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Supercomputing centers are unique resources that aim to enable scientific knowledge discovery by employing large computational resources-the 'Big Iron.' Design, acquisition, installation, and management of the Big Iron are carefully planned and monitored. Because these Big Iron systems produce a tsunami of data, it's natural to colocate the visualization and analysis infrastructure. This infrastructure consists of hardware (Little Iron) and staff (Skinny Guys). Our collective experience suggests that design, acquisition, installation, and management of the Little Iron and Skinny Guys doesn't receive the same level of treatment as that of the Big Iron. This article explores the following questions about the Little Iron: How should we size the Little Iron to adequately support visualization and analysis of data coming off the Big Iron? What sort of capabilities must it have? Related questions concern the size of visualization support staff: How big should a visualization program be-that is, how many Skinny Guys should it have? What should the staff do? How much of the visualization should be provided as a support service, and how much should applications scientists be expected to do on their own?
Tree visualization is one of the best-studied areas of information visualization; researchers have developed more than 200 visualization and layout techniques for trees. The *** project aims to provide a hand-curated ...
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Tree visualization is one of the best-studied areas of information visualization; researchers have developed more than 200 visualization and layout techniques for trees. The *** project aims to provide a hand-curated bibliographical reference to this ever-growing wealth of techniques. It offers a visual overview that users can filter to a desired subset along the design criteria of dimensionality, edge representation, and node alignment. Details, including links to the original publications, can be brought up on demand. *** has become a community effort, with researchers sending in preprints of their tree visualization techniques to be published or pointing out additional information. [ABSTRACT FROM PUBLISHER]
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