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Mean Shift
Mean shift is a non-parametric feature space, feature-space mathematical analysis technique for locating the maxima of a density function, a so-called mode (statistics), mode-seeking algorithm. Application domains include cluster analysis in computer vision and image processing. History The mean shift procedure is usually credited to work by Fukunaga and Hostetler in 1975. It is, however, reminiscent of earlier work by Schnell in 1964. Overview Mean shift is a procedure for locating the maxima—the Mode (statistics), modes—of a density function given discrete data sampled from that function. This is an iterative method, and we start with an initial estimate x . Let a Kernel (statistics), kernel function K(x_i - x) be given. This function determines the weight of nearby points for re-estimation of the mean. Typically a Radial basis function kernel, Gaussian kernel on the distance to the current estimate is used, K(x_i - x) = e^ . The weighted mean of the density in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Non-parametric
Nonparametric statistics is the branch of statistics that is not based solely on parametrized families of probability distributions (common examples of parameters are the mean and variance). Nonparametric statistics is based on either being distribution-free or having a specified distribution but with the distribution's parameters unspecified. Nonparametric statistics includes both descriptive statistics and statistical inference. Nonparametric tests are often used when the assumptions of parametric tests are violated. Definitions The term "nonparametric statistics" has been imprecisely defined in the following two ways, among others: Applications and purpose Non-parametric methods are widely used for studying populations that take on a ranked order (such as movie reviews receiving one to four stars). The use of non-parametric methods may be necessary when data have a ranking but no clear numerical interpretation, such as when assessing preferences. In terms of levels of meas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |