Volume 18, Issue 2

A color-based segmentation scheme applied to dermatoscopic images is proposed. The RGB image is processed in the L*u*v* color space. A 2D histogram is computed with the two principal components and then smoothed with a Gaussian low-pass filter. The maxima location and a set of features are computed from the histogram contour lines. These features are the number of enclosed pixels, the surface of the base and the height of the maximum. They allow for the selection of valid clusters which determine the number of classes. The image is then segmented using a modified version of the fuzzy c-means (FCM) clustering technique that takes into account the cluster orientation. Finally, the segmented image is cleaned using mathematical morphology, the region borders are smoothed and small components are removed.

提出了一种基于颜色的分割方案，应用于皮肤镜图像。RGB图像在L*u*v*颜色空间中处理。用两个主成分计算二维直方图，然后用高斯低通滤波器平滑。从直方图轮廓线计算最大值位置和一组特征。这些特征包括封闭像素数、基底面积和最大值高度。它们允许选择有效的聚类，从而确定类别数。然后使用考虑聚类方向的改进模糊C均值（FCM）聚类技术对图像进行分割。最后，使用数学形态学清理分割后的图像，平滑区域边界并移除小区域。

Describes an approach to boundary detection in ultrasound speckle based on an image enhancement technique. The enhancement algorithm works by filtering the image with "sticks", short line segments which are varied in orientation to achieve the maximum projected value at each point. In this paper, we present three significant extensions to improve the performance of the basic method. First, we inve...

描述了一种基于图像增强技术的超声散斑边界检测方法。该增强算法通过使用“棒状”短线段对图像进行滤波，这些线段的方向变化以在每个点获得最大投影值。本文提出了三个重要的扩展来改进基本方法的性能。首先，我们研究了...

A blinded evaluation of two groups of retrospective image registration techniques was performed using as a gold standard a prospective marker-based registration method, and we compared the performance of one group with the other. By grouping the techniques as volume-based or surface-based, we could make some interesting conclusions. In order to ensure blindness, all retrospective registrations wer...

采用前瞻性基于标记的配准方法作为金标准，对两组回顾性图像配准技术进行了盲法评估，并比较了其中一组与另一组的性能。通过将技术分为基于体积或基于表面的方法，我们可以得出一些有趣的结论。为确保盲法，所有回顾性配准都...

A statistical method for detecting activated pixels in functional MRI (fMRI) data is presented. In this method, the fMRI time series measured at each pixel is modeled as the sum of a response signal which arises due to the experimentally controlled activation-baseline pattern, a nuisance component representing effects of no interest, and Gaussian white noise. For periodic activation-baseline patte...

提出了一种用于检测功能磁共振成像（fMRI）数据中激活像素的统计方法。在该方法中，每个像素处的fMRI时间序列被建模为响应信号（由实验控制的激活-基线模式引起）、不感兴趣的干扰效应和高斯白噪声之和。对于周期性激活-基线模式...

The solution to the bioelectromagnetic inverse problem is discussed in terms of a generalized lead field expansion, extended to weights depending polynomially on the current strength. The expansion coefficients are obtained from the resulting system of equations which relate the lead field expansion to the data. The framework supports a family of algorithms which include the class of minimum norm ...

讨论了生物电磁逆问题的解，将其推广到广义导联场展开，扩展到权重与电流强度成多项式关系的情况。展开系数从导联场展开与数据相关的方程组中获得。该框架支持一系列算法，包括最小范数类……

The estimation of parameters in radio-tracer models from positron emission tomography (PET) data by nonlinear least squares (NLS) often leads to results with unacceptable mean square error (MSE) characteristics. The introduction of constraints on parameters has the potential to address this problem. We examine a ridge regression technique that augments the standard NLS criterion by the addition of a term which penalizes estimates which deviate from physiologically reasonable values. A variation on a plug-in methodology of Hoerl et al. (1975) is examined for data-dependent selection of the degree of reliance to place on the penalizing term. A simulation study is carried out to evaluate the performance of this approach in the context of estimation of kinetic constants in the three-compartment model used to analyze data from PET studies with fluoro-deoxyglucose (FDG). The results show that, over a range of realistic noise levels, the ridge regression procedure can be expected to reduce the root MSE of parameter estimates by 60%. This result is not found to be substantially dependent on the precise formulation of the penalty function used. Thus, the use of ridge regression for the estimation of kinetic parameters in PET studies is thus considered to be a promising tool.

通过非线性最小二乘法(NLS)从正电子发射断层扫描(PET)数据估计放射性示踪剂模型中的参数通常会导致具有不可接受的均方误差(MSE)特性的结果。引入参数约束有可能解决这个问题。我们研究了一种岭回归技术，该技术通过添加...

Evaluates a segmentation technique for magnetic resonance (MR) images of the brain based on fuzzy algorithms for learning vector quantization (FALVQ). These algorithms perform vector quantization by updating all prototypes of a competitive network through an unsupervised learning process. Segmentation of MR images is formulated as an unsupervised vector quantization process, where the local values...

评估了一种基于模糊学习矢量量化（FALVQ）算法的脑部磁共振（MR）图像分割技术。这些算法通过无监督学习过程更新竞争网络的所有原型来执行矢量量化。MR图像分割被表述为一个无监督的矢量量化过程，其中局部值...

Image interpolation is an important operation that is widely used in medical imaging, image processing and computer graphics. A variety of interpolation methods are available in the literature. However, their systematic evaluation is lacking. In a previous paper (ibid., vol. 15, pp. 881-92, Dec. 1996), we presented a framework for the task-independent comparison of interpolation methods based on c...

图像插值是医学成像、图像处理和计算机图形学中广泛使用的重要操作。文献中提供了多种插值方法，但缺乏系统评估。在之前的一篇论文中（同上，第15卷，第881-92页，1996年12月），我们提出了一个基于c...的任务无关插值方法比较框架。

An adaptive predictive multiplicative autoregressive (APMAR) method is proposed for lossless medical image coding. The adaptive predictor is used for improving the prediction accuracy of encoded image blocks in our proposed method. Each block is first adaptively predicted by one of the seven predictors of the JPEG lossless mode and a local mean predictor. It is clear that the prediction accuracy o...

提出了一种用于无损医学图像编码的自适应预测乘法自回归（APMAR）方法。在我们提出的方法中，自适应预测器用于提高编码图像块的预测精度。每个块首先由JPEG无损模式的七个预测器之一和局部均值预测器进行自适应预测。显然，预测精度...