Oct 28th, 2009| 09:29 am | Posted by hlee

As a part of exploring spatial distribution of particles/objects, not to approximate via Poisson process or Gaussian process (parametric), nor to impose hypotheses such as homogenous, isotropic, or uniform, various **nonparametric** methods somewhat dragged my attention for data exploration and preliminary analysis. Among various nonparametric methods, the one that I fell in love with is tessellation (state space approaches are excluded here). Computational speed wise, I believe tessellation is faster than kernel density estimation to estimate level sets for multivariate data. Furthermore, conceptually constructing polygons from tessellation is intuitively simple. However, coding and improving algorithms is beyond statistical research (check books titled or key-worded partially by **computational geometry**). Good news is that for computation and getting results, there are some freely available softwares, packages, and modules in various forms. Continue reading ‘[ArXiv] Voronoi Tessellations’ »

Tags:

data compression,

delanay tessellation,

density estimation,

image processing,

nonparametric,

spatial statistics,

van de Weygaert,

van Lieshout,

voronoi tessellation Category:

Algorithms,

arXiv,

Galaxies,

Methods |

Comment
Sep 22nd, 2009| 12:03 pm | Posted by hlee

Thanks to a Korean solar physicist^{[1]} I was able to gather the following websites and some relevant information on Space Weather Forecast in action, not limited to literature nor toy data.

Continue reading ‘More on Space Weather’ »

Tags:

automatic,

CME,

computer vision,

data mining,

feature detection,

filament,

image processing,

machine learning,

manifold,

space weather,

statistical learning,

sunspot,

SVM Category:

Algorithms,

arXiv,

Cross-Cultural,

Data Processing,

Imaging,

Jargon |

Comment
Sep 11th, 2009| 03:40 pm | Posted by hlee

A number of practical Bayesian data analysis books are available these days. Here, I’d like to introduce two that were relatively recently published. I like the fact that they are rather technical than theoretical. They have practical examples close to be related with astronomical data. They have R codes so that one can try algorithms on the fly instead of jamming probability theories. Continue reading ‘[Books] Bayesian Computations’ »

Tags:

book,

BUGS,

CMB,

examples,

HMM,

identifiability,

image processing,

LLN,

mixture,

MRF,

R Category:

Bayesian,

Fitting,

Languages,

MC,

MCMC,

Methods,

Stat |

1 Comment
Sep 1st, 2009| 07:43 pm | Posted by hlee

[arxiv:0906.3662] **The Statistical Analysis of fMRI Data** by Martin A. Lindquist

Statistical Science, Vol. 23(4), pp. 439-464

This review paper offers some information and guidance of statistical image analysis for fMRI data that can be expanded to astronomical image data. I think that fMRI data contain similar challenges of astronomical images. As Lindquist said, collaboration helps to find shortcuts. I hope that introducing this paper helps further networking and collaboration between statisticians and astronomers.

**List of similarities** Continue reading ‘[ArXiv] Statistical Analysis of fMRI Data’ »

Tags:

data aquisition,

experimental design,

fMRI,

ICA,

image analysis,

image processing,

localization,

modeling,

pipeline,

preprocessing,

similarities,

Spatial,

temporal,

time series,

voxel Category:

arXiv,

Cross-Cultural,

Data Processing,

Imaging,

Jargon,

Methods,

Stat |

Comment
Jun 12th, 2009| 03:47 pm | Posted by hlee

**A Fast Thresholded Landweber Algorithm for Wavelet-Regularized Multidimensional Deconvolution**

Vonesch and Unser (2008)

IEEE Trans. Image Proc. vol. 17(4), pp. 539-549

Quoting the authors, I also like to say that __the recovery of the original image from the observed is an __**ill-posed** problem. They traced the efforts of wavelet regularization in deconvolution back to a few relatively recent publications by astronomers. Therefore, I guess the topic and algorithm of this paper could drag some attentions from astronomers. Continue reading ‘Wavelet-regularized image deconvolution’ »

Tags:

bound optimization,

deconvolution,

image processing,

impulse response,

MM algorithm,

PSF,

regularization,

restoration,

thresholding,

wavelet Category:

Algorithms,

arXiv,

Data Processing,

Fitting,

Imaging,

Jargon,

Methods,

Quotes,

Stat |

Comment
Dec 7th, 2008| 11:23 pm | Posted by hlee

MADS stands for **“Missing in ADS.”** Every astronomer, I believe, knows what ADS is. As we have [EotW] series and used to have [ArXiv] series, creating a new series for semi-periodic postings under the well known name ADS seems interesting. Continue reading ‘[MADS] HMM’ »

Oct 24th, 2007| 09:15 pm | Posted by hlee

My friend’s blog led me to Terrence Tao’s blog. A mathematician writes topics of applied mathematics and others. A glance tells me that all postings are well written. Especially, compressed sensing and single pixel cameras drags my attention more because the topic stimulates thoughts of astronomers in *virtual observatory*^{[1]} and *image processing*^{[2]} (it is not an exaggeration that observational astronomy starts with taking pictures in a broad sense) and statisticians in multidimensional applications, not to mention engineers in signal and image processing. Continue reading ‘compressed sensing and a blog’ »