摘要:

An existing Poisson random variate generator is made compact and portable by introducing pre-tests into the rejection routine.

ISSN:0266-4763    

DOI:10.1080/02664768900000048

出版商:Carfax Publishing Company    

年代:1989

数据来源: Taylor

摘要:

Many of the tasks encountered in image processing can be considered as problems in statistical inference. In particular, they fit naturally into a subjectivist Bayesian framework. In this paper, we describe the Bayesian approach to image analysis. Numerical examples are not included but can be found among the references, in the previous Special Issue of this Journal and elsewhere. It is argued that the Bayesian approach, still in its infancy, has considerable potential for future development.

ISSN:0266-4763    

DOI:10.1080/02664768900000049

出版商:Carfax Publishing Company    

年代:1989

数据来源: Taylor

摘要:

Let T be a two-dimensional region, and let X be a surface dejined on T. The values of X on T, constitute an image, or pattern. The true value of X at any point on T cannot be directly observed, but data can be recorded which provide information about X. The aim is to reconstruct X using the prior knowledge that X will vary smoothly over most of T, but may exhibit jump discontinuities over line segments. This information can be incorporated via Bayes' theorem, using a polygonal Markov random field on T as prior distribution. Under this continuum model, X may in principle be estimated according to standard criteria. In practice, the techniques rely on simulation of the posterior distribution. A natural family of conjugate priors is identified, and a class of spatial-temporal Markov processes is constructed on the uncountable state space; simulation then proceeds by a method of analogous to the Gibbs sampler.

ISSN:0266-4763    

DOI:10.1080/02664768900000050

出版商:Carfax Publishing Company    

年代:1989

数据来源: Taylor

摘要:

In image analysis, the shape of an object in a 2-dimensional image is usually summarised by some suitable feature descriptors. One method is to use the image moments for which we introduce area corrections since images are only observed on a discrete lattice. In particular, moment invariants (Hu, 1962; Barton & David, 1962) are constructed which are invariant under translation, rotation and dilation of spatial variables and rescaling of response variables. We critically examine the low order moments. In particular, it is known that any function of the invariants could be used and we propose invariants which stabilise the variance. Variance stabilising transformations are derived and their behaviour is examined for pure and segmented objects. It is shown that unbiased estimates of the population size are obtained under naive thresholding when the object and background are of equal size. Our results indicate how an improved feature vector can be obtained by utilising a suitable combination of variance stabilised moment invariants and the moment invariants themselves. The synthetic examples given here are motivated by real infra-red images containing objects of interest and back-ground. We also examine other moments and approaches including the use of the shape space itself.

ISSN:0266-4763    

DOI:10.1080/02664768900000051

出版商:Carfax Publishing Company    

年代:1989

数据来源: Taylor

ISSN:0266-4763    

DOI:10.1080/02664768900000052

出版商:Carfax Publishing Company    

年代:1989

数据来源: Taylor

ISSN:0266-4763    

DOI:10.1080/02664768900000053

出版商:Carfax Publishing Company    

年代:1989

数据来源: Taylor

ISSN:0266-4763    

DOI:10.1080/02664768900000054

出版商:Carfax Publishing Company    

年代:1989

数据来源: Taylor

ISSN:0266-4763    

DOI:10.1080/02664768900000055

出版商:Carfax Publishing Company    

年代:1989

数据来源: Taylor