A wavelet based multiresolution algorithm for rotation invariant feature extraction

The present work aims at proposing a new wavelet representation formula for rotation invariant feature extraction. The algorithm is a multilevel representation formula involving no wavelet decomposition in standard sense. Using the radial symmetry property, that comes inherently in the new representation formula, we generate the feature vectors that are shown to be rotation invariant. We show that, using a hybrid data mining technique, the algorithm can be used for rotation invariant content based image retrieval (CBIR). The proposed rotation invariant retrieval algorithm, suitable for both texture and nontexture images, avoids missing any relevant images but may retrieve some other images which are not very relevant. We show that the higher precision can however be achieved by pruning out irrelevant images.     

Basic research problems in remote sensing

In this paper we describe the sources of geometric errors and methods to correct them with special reference to satellite-derived multi-spectral data. We then give an overview of an atmospheric model which can correct for atmospheric distortions. These are followed by discipline-oriented problems. We conclude by looking at some of the future remote sensing satellites which can cater to the problems referred to above.     

Data processing in remote sensing

A brief overview of pattern recognition and image processing with special emphasis on the first topic and its application to remote sensing is presented. Some of the recent areas of work in pattern recognition are also highlighted.     

Quantitative evaluation of enhancement techniques

Enhancement techniques are often used in image processing. In this paper, a quantitative measure of the image quality through evaluation of the coefficient of information content and the entropy has been suggested to evaluate the effect of enhancement. The image has been assumed to be a sample function of a homogeneous random field and the pixel values are estimated from the ‘past’ pixel values. The difference between the estimated value and the actual value of the pixel has been used as the criterion for defining the coefficient of information content. Also, the entropy obtained using the co-occurrance matrix of the image, has been used as a quantitative measure of the image quality. Measurements of the image quality through the evaluation of the coefficient of information content and the entropy have been carried out for the test images and the results of these measurements have been presented.     

Generalized isocline method of plotting phase-plane trajectories

By considering simultaneously theN-x(or theN-dot{x}), whereN=ddot{x}/dxand thedot{x}-xplanes, second order non-linear autonomous systems (not easily amendable to the existing methods) described by the differential equationddot{x}=F(x, dot{x})can be studied. Changes in system behavior due to changes in initial conditions, nonlinear dampling and restoring forces can easily be studied. Simple and general as it is, the method presented here is believed to be novel.