17,142 research outputs found
Recommended from our members
Use of colour for hand-filled form analysis and recognition
Colour information in form analysis is currently under utilised. As technology has advanced and computing costs have reduced, the processing of forms in colour has now become practicable. This paper describes a novel colour-based approach to the extraction of filled data from colour form images. Images are first quantised to reduce the colour complexity and data is extracted by examining the colour characteristics of the images. The improved performance of the proposed method has been verified by comparing the processing time, recognition rate, extraction precision and recall rate to that of an equivalent black and white system
New approaches to probing Minkowski functionals
We generalize the concept of the ordinary skew-spectrum to probe the effect of non-Gaussianity
on the morphology of cosmic microwave background (CMB) maps in several domains: in
real space (where they are commonly known as cumulant-correlators), and in harmonic and
needlet bases. The essential aim is to retain more information than normally contained in these
statistics, in order to assist in determining the source of any measured non-Gaussianity, in the
same spirit as Munshi & Heavens skew-spectra were used to identify foreground contaminants
to the CMB bispectrum in Planck data. Using a perturbative series to construct the Minkowski
functionals (MFs), we provide a pseudo-C based approach in both harmonic and needlet
representations to estimate these spectra in the presence of a mask and inhomogeneous noise.
Assuming homogeneous noise, we present approximate expressions for error covariance for
the purpose of joint estimation of these spectra. We present specific results for four different
models of primordial non-Gaussianity local, equilateral, orthogonal and enfolded models, as
well as non-Gaussianity caused by unsubtracted point sources. Closed form results of nextorder
corrections to MFs too are obtained in terms of a quadruplet of kurt-spectra. We also
use the method of modal decomposition of the bispectrum and trispectrum to reconstruct the
MFs as an alternative method of reconstruction of morphological properties of CMB maps.
Finally, we introduce the odd-parity skew-spectra to probe the odd-parity bispectrum and its
impact on the morphology of the CMB sky. Although developed for the CMB, the generic
results obtained here can be useful in other areas of cosmology
- âŠ