利用Kolmogorov-Smirnov统计的区域化图像分割
Regionalized image segmentation using Kolmogorov-Smirnov statistics
- 2015年20卷第5期 页码:678-686
网络出版:2015-05-07,
纸质出版:2015
DOI: 10.11834/jig.20150510
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网络出版:2015-05-07,
纸质出版:2015
移动端阅览
为了在未知或无法建立图像模型的情况下
实现统计图像分割
提出一种结合Voronoi几何划分、K-S(Kolmogorov-Smirnov)统计以及M-H(Metropolis-Hastings)算法的图像分割方法. 首先利用Voronoi划分将图像域划分成不同的子区域
而每个子区域为待分割同质区域的一个组成部分
并利用K-S统计定义类属异质性势能函数
然后应用非约束吉布斯表达式构建概率分布函数
最后采用M-H算法进行采样
从而实现图像分割. 采用本文算法
分别对模拟图像、合成图像、真实光学和SAR图像进行分割实验
针对模拟图像和合成图像
分割结果精度均达到98%以上
取得较好的分割结果. 提出基于区域的图像分割算法
由于该算法中图像分割模型的建立无需原先假设同质区域内像素光谱测度的概率分布
因此提出算法具有广泛的适用性.为未知或无法建立图像模型的统计图像分割提供了一种新思路.
Image segmentation is a critical step in image processing. Several algorithms based on statistics have been proposed
in which the statistical image model must be built under a certain assumption on the image. For example
the commonly used statistical model on pixel intensities includes normal distribution and gamma distribution (especially for SAR intensities image). Although optimal segmentation results could be obtained through most algorithms
statistical models are an approximation of pixel intensities and could not accurately describe the characteristics. Moreover
building an accurate image model
especially for remote sensing images
is difficult because of the complexity and uncertainty of spectral characteristics of objects on the earth's surface. Kolmogorov-Smimov statistic (K-S distance) defines the similarity by measuring the maximum distance of two statistical distributions. In this case
building a statistical model for an image is not necessary. By contrast
grayscale histogram could be used to describe the distribution of two classes for image segmentation tasks. K-S distance solves the difficulty in building an accurate statistic distribution model for an image. To date
K-S distance image processing is based only on pixel scale. Given that histogram is not sensitive when only a pixel changes its class
K-S distance based segmentation could not be used. In this paper
region and K-S distance based image segmentation was proposed. Voronoi tessellation was used to partition image domain into sub-regions (Voronoi polygons) corresponding to the components of homogenous regions. Each Voronoi polygon was assigned a random variable as label to indicate the homogenous region to which it belongs. All labels for the Voronoi polygons formed a label field. The intensity histogram of each homogenous region was then calculated
and the dissimilarity between two homogenous regions was determined by the K-S distance on the two histograms corresponding to the two regions. Thereafter
the potential energy function of the dissimilarity was constructed. Employing Bayesian inference
a posterior distribution was obtained using the likelihood constructed by non-constrained Gibbs expression. Finally
Metropolis-Hastings (M-H) scheme included updating labels
moving generation points
and birth and death generation points operations designed to simulate the posterior. The optimal segmentation was obtained by Maximum A Posterior (MAP) estimation. Using the proposed algorithm
segmentation was performed on simulated and synthesized images
as well as real optical and SAR images. Qualitative and quantitative accuracy evaluations were carried out to assess the effectiveness of the proposed algorithm. In addition
results from both proposed algorithm and pixel and statistic based segmentation algorithm are compared and show that the proposed algorithm performed significantly better. The analysis on the regionalized image segmentation algorithm based on K-S statistics does not need to build an image model and could be viewed as regional based algorithm to avoid the effect of image noise during segmentation. To improve the accuracy of fitting homogeneous regions with partitioned sub-regions
different geometry tessellation methods must be considered to partition the image domain. Furthermore
the proposed methodology will be developed for image segmentation with variable classes.
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