the estimation of left ventricle motion and deformation from series of images has been an area of attention in the medical image analysis and still remains and open and challenging problem. the proper motion tracking ...
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ISBN:
(纸本)0769513301
the estimation of left ventricle motion and deformation from series of images has been an area of attention in the medical image analysis and still remains and open and challenging problem. the proper motion tracking of left ventricle wall can contribute to isolate the location and extent of ischemic or infarcted myocardium. We present a method that automatically estimates the velocity vector field for a beating heart based on the study of variation in frequency content of a time series of non-stationary images. Results obtained withthis automated method in synthetic images and cardiac gated-SPECT images are presented.
作者：
Clua, EWGDreux, MFeijó, BICAD
Department of Computer Science PUC - Rio Brazil ICAD
Department of Mechanical Engineering PUC - Rio Brazil
In order to obtain models of complex virtual environments, there are many solutions that make use of image-based rendering techniques. When using a set of images to represent an element in space as a billboard, there ...
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ISBN:
(纸本)0769513301
In order to obtain models of complex virtual environments, there are many solutions that make use of image-based rendering techniques. When using a set of images to represent an element in space as a billboard, there are some problems related withthe shading calculations, once these elements are just planes in space. this article presents a new approach for shading objects represented by images, which divides the problem into two parts: the shading maps generation for an object with specific set of lights in the environment and real-time shading simulation for a specific observer point of view and object location.
fMRI is a non-invasive technique to evaluate brain areas related to a requested task. the event-related fMRI is one kind of its design, which permits not only spatial resolution, but also temporal correlation. this in...
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ISBN:
(纸本)0769513301
fMRI is a non-invasive technique to evaluate brain areas related to a requested task. the event-related fMRI is one kind of its design, which permits not only spatial resolution, but also temporal correlation. this information may be more easily understood by the clinicians, if showed in a dynamic way. the aim of this paper is to describe a fMRI visualization system to expose the brain images, in the best view to stand out the areas of activity as long as they appear. It will empower the technique, not only to impress the clinicians, but also to enhance the importance of temporal connectivities. this system will be a module of the CAVERNA virtual reality.
this paper proposes a new method for image denoising with edge preservation, based on image multiresolution decomposition by a redundant wavelet transform. In our approach, edges are implicitly located and preserved i...
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ISBN:
(纸本)0769513301
this paper proposes a new method for image denoising with edge preservation, based on image multiresolution decomposition by a redundant wavelet transform. In our approach, edges are implicitly located and preserved in the wavelet domain, while noise is filtered out. At each resolution, the coefficients associated to noise and coefficients associated to edges are modeled by Gaussians, and a shrinkage function is assembled. the shrinkage functions are combined in consecutive resolution, and geometric constraints are applied to preserve edges that are not isolated. Finally, the inverse wavelet transform is applied to the modified coefficients. this method is adaptive, and performs well for images contaminated by natural and artificial noise.
this paper presents an interactive algorithm for image denoising and segmentation. A global competition criterion is used to impose an order of processing on all image pixels. the smoothing step employs an evolution e...
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ISBN:
(纸本)0769513301
this paper presents an interactive algorithm for image denoising and segmentation. A global competition criterion is used to impose an order of processing on all image pixels. the smoothing step employs an evolution equation controlled by the local curvature to denoise the image while preserving the features. the interactive segmentation step requires the user to select one definitive seed per region. Region growing is initiated around provisory seeds, which are automatically detected, labeled and eventually merged by the algorithm. A simple merging mechanism is used to handle the topological transformations required to remove the image over-segmentation. It is shown that accurate and fast segmentation results can be achieved for gray and color images using this simple method. Extension to 3D images is straightforward and easily handled.
this paper presents a novel approach to the real-time rendering of complex scenes problem. Up to the present date, a huge number of acceleration techniques have been proposed, although most are geared towards a specif...
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ISBN:
(纸本)0769513301
this paper presents a novel approach to the real-time rendering of complex scenes problem. Up to the present date, a huge number of acceleration techniques have been proposed, although most are geared towards a specific kind of scene. Instead of using a single, or a fixed set of rendering acceleration techniques, we propose the use of several, and to select the best one based on the current viewpoint. thus, dynamically adapting the rendering process to the contents of the scene, it is possible to take advantage of all these techniques when they are better suited, rendering scenes that would otherwise be too complex to display at interactive frame rates. We describe a framework capable of achieving this purpose, consisting on a pre-processor and an interactive rendering engine. the framework is geared towards interactive applications were a complex and large scene has to be rendered at interactive frame rates. Finally, results taken from our test implementation are given.
this paper exposes an algorithm which leads to a fuzzy segmentation. this algorithm performs, as in the watershed method, a progressive flood of the gradient image from pixels of lowest gradients. It uses a new distan...
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ISBN:
(纸本)0769513301
this paper exposes an algorithm which leads to a fuzzy segmentation. this algorithm performs, as in the watershed method, a progressive flood of the gradient image from pixels of lowest gradients. It uses a new distance, called topographic distance. Any local minimum of the gradient norm image constitutes a seed for the region g-rowing, avoiding the use of a marker image. these seeds constitute the cores of the initial fuzzy regions. then the sites are gradually agglomerated to the region, while their membership degrees to the region decrease, according to the distance to the core and to the gradient norms, by the way of the topographic distance. the numerous fuzzy regions are then merged and the membership degrees of pixels to final regions are computed. Applications concern crisp segmentation of colour or gray scale images and pattern recognition from fuzzy regions.
this paper presents image-synthesis techniques to define, animate and visualize scenes simulating the behavior of the open-sea surface. Wave modeling is obtained by means of the bump mapping technique. Wave texture, d...
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ISBN:
(纸本)0769513301
this paper presents image-synthesis techniques to define, animate and visualize scenes simulating the behavior of the open-sea surface. Wave modeling is obtained by means of the bump mapping technique. Wave texture, defined by noise functions, is applied by means of a solid-space animation technique to generate surface animation. An implementation based on the Phong model is used to determine diffuse and specular reflections. As a result of the synthesis process, a set of frames is obtained, to be used to compose the animation.
In this paper we present a computational framework for semi-automated assessment of skeletal age based on a multi-scale image analysis approach. through 2D digital X-ray images of the left hand, maturity indicators ar...
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ISBN:
(纸本)0769513301
In this paper we present a computational framework for semi-automated assessment of skeletal age based on a multi-scale image analysis approach. through 2D digital X-ray images of the left hand, maturity indicators are searched by means of a two-step process: the user interactively indicates a point inside the middle finger, and the computational method analyzes the image intensity profile, along this line, searching for physiological signatures related to different epiphyseal events (ossification, cartilage stage, early fusion and complete fusion). A scale-space approach is used to select the best scale to enhance the edges between the bones and soft tissues. Initial results indicate that this approach could be useful to facilitate the analysis of growth disorders in pediatrics.
this poster describes a technique for reconstructing tomographic images generated by a minitomograph scanner for soil science developed by Embrapa Agricultural Instrumentation using a parallel DSP architecture with an...
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ISBN:
(纸本)0769513301
this poster describes a technique for reconstructing tomographic images generated by a minitomograph scanner for soil science developed by Embrapa Agricultural Instrumentation using a parallel DSP architecture with an HEPC2E board from Hunt Engineering with two TMS320C40 processors from Texas Instruments. the software designed for visualization of bi-and tri-dimensional images uses Code Composer tool combined with Parallel C from 3L and Borland Builder C++. Reconstruction and interpolation tasks were distributed throughout the platform processors, using parallel algorithms in order to improve speed and processing power. the work resulted in an increase of about 15% in the system speed when compared withthat reached using a classical platform at 200 MHz.
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