Stanley S. Ipson

Feature Recognition in Solar Images

Despite several decades of research and development in the field of pattern recognition, the general problem of recognizing complex patterns with arbitrary orientations, locations, and scales remains unsolved and normally is applied using iterative manual evaluation of the detection results. This problem is becoming increasingly important with the growing number of massive archives of solar images produced by instruments located at ground-based observatories and aboard current satellites such as YOHKOH, SOHO and TRACE, with future satellites such as SOLAR B, SDO and STEREO in prospect. The size of expected archives requires a new automated approach to digital image processing and data extraction with robust and efficient pattern recognition techniques to be developed and implemented. This review evaluates techniques for the standardisation in shape and intensity of solar images and summarises the existing manual and semi-automated feature recognition techniques applied to a representative range of solar features, including sunspots, filaments, active regions, flares, coronal mass ejections and magnetic neutral lines. The review also surveys the most recent fully-automated detection techniques developed for the creation of Solar Feature Catalogues of sunspots, active regions and filaments for the European Grid of Solar Observations. The survey is aimed to help researchers and students to learn about the recognition techniques applied to astrophysical images with different levels of noise and distortions and to work effectively with the Solar Feature Catalogue.

A study of the 140Ce(d, p) and 142Nd(d, p) reactions at 19 MeV

Abstract The 140 Ce(d, p) and 142 Nd(d, p) reactions have been studied at an incident deuteron energy of 19 MeV using the injector-tandem accelerator and the multichannel magnetic spectrograph of the University of Oxford. Deuteron optical-model parameters have been obtained from the analyses of elastic scattering experiments on enriched 140 Ce and 142 Nd targets. The parameters have been used to calculate theoretical (d, p) angular distributions on the basis of the DWBA. Orbital angular momentum transfers have been deduced and spectroscopic factors have been determined for almost all the levels observed up to an excitation energy of 3.5 MeV in 141 Ce and 143 Nd. The spectroscopic information is more complete than that derived from previous studies, and agrees satisfactorily with expected sum-rule limits. Unified- model calculations have been made of odd-parity states and very good agreement with the experimental spectra of nuclei having N = 83 has been found.

A comparative study of digital watermarking in JPEG and JPEG 2000 environments

JPEG 2000 is a new compression technology that achieves very high compression rate and maintains visual quality, Digital watermarking techniques have been developed to protect the copyright of media signals. The goal of this paper is to put into perspective joint photographic experts group (JPEG) and JPEG 2000 concepts a long with watermarking principle. It provides evaluation of the compatibility aspects of JPEG 2000 versus JPEG standard with watermarking. Various experiments have been conducted to compare the performance of both standards under various conditions. An outlook on the future of digital image watermarking within JPEG 2000 is introduced.

Knowledge-Based Baseline Detection and Optimal Thresholding for Words Segmentation in Efficient Pre-Processing of Handwritten Arabic Text

Techniques on detecting baseline and segmenting words in handwritten Arabic text are presented in this paper. Instead of using pure projection, knowledge of the location of the baseline is utilized for accurate baseline detection. Then, distances between words and subwords are respectively analyzed, and their statistical distributions are obtained to decide an optimal threshold in segmenting words. Results on IFN/ENIT database have validated our methods in terms of improved baseline detection and words segmentation for further recognition.

Experimental and shell-model studies of the reactions 91Zr(d, p)92Zr and 90Zr(t, p)92Zr

Abstract The results of high-resolution studies of the 91 Zr(d, p) reaction at E d = 12 MeV and the 90 Zr(t, p) reaction at E t = 11.85 MeV are presented. Absolute cross sections have been measured for both reactions and (d, p) spectroscopic factors determined. A comparison of these results with earlier data has been made, and although many of the previous assignments have been confirmed, many new features concerning the structure of 92 Zr have been discovered. Shell-model calculations have been performed for 91 Zr and 92 Zr using a neutron space which includes the 2 d 5 2 , 3 s 1 2 , 2 d 3 2 , 1 g 7 2 and 1 h 11 2 orbits and a proton space comprising the 1 g 9 2 and 2 p 1 2 orbits. Realistic proton-neutron and neutron-neutron interactions based on the Sussex matrix elements were used in the calculations. Spectroscopic factors have been calculated for the 90 Zr(d, p) and 91 Zr(d, p) reactions and cross sections calculated for the 90 Zr(t, p) reaction. In general, good agreement between the theoretical and the experimental results has been obtained.

Systematics of l=6 (d,p) transitions in N=83 nuclei and a unified-model interpretation

Abstract The reactions 138 Ba, 140 Ce, 142 Nd, 144 Sm(d, p) have been studied at an incident deuteron energy of 19 MeV using the injector-tandem accelerator and the multichannel magnetic spectrograph at the University of Oxford. Two strong l = 6 transitions to 13 2 + states have been found in each of these nuclei. DWBA calculations have been made and spectroscopic factors deduced. A unified-model interpretation of these states is presented and good agreement with the experimental data has been found. Excitation energies of other positive-parity states have been calculated and compared with existing experimental information.

A novel triangulation procedure for thinning hand-written text

Abstract This paper describes a novel procedure for thinning binary text images by generating graphical representations of words within the image. A smoothed polygonal approximation of the boundaries of each word is first decomposed into a set of contiguous triangles. Each triangle is then classified into one of only three possible types from which a graph is generated that represents the topological features of the object. Joining graph points with straight lines generates a final polygon skeleton that, by construction, is one pixel wide and fully connected. Results of applying the procedure to thinning Arabic and English handwriting are presented. Comparisons of skeleton structure and execution time with results from alternative techniques are also presented. The procedure is considerably faster than the alternatives tested when the image resolution is greater than 600 dpi and the graphical representation often needed in subsequent recognition steps is available without further processing.

Word-based handwritten Arabic scripts recognition using DCT features and neural network classifier

In this paper, a system is proposed for word-based recognition of handwritten Arabic scripts. Techniques are discussed in details in terms of three stages in the system, i.e. preprocessing, feature extraction and classification. Firstly, words are segmented from inputted scripts and also normalized in size. Then, DCT features are extracted for each word sample. Finally, these features are then utilized to train a neural network for classification. The proposed system has been successfully tested on database (version v2.0p1e) consisting of 32492 Arabic words handwritten by more than 1000 different writers, and the results were promising and very encouraging.

Applications of a direct algorithm for the rectification of uncalibrated images

An algorithm for the rectification of uncalibrated images is presented and applied to a variety of cases. The algorithm generates the rectifying transformations directly from the geometrical relationship between the images, using any three correspondences in the images to define a reference plane. A small set of correspondences is used to calculate an initial rectification. Additional correspondences are introduced semi-automatically, by correlating regions of the rectified images. Since the rectified images of surfaces in the reference plane have no relative distortion, features can be matched very accurately by correlation, allowing small changes in disparity to be detected. In the 3-d reconstruction of an architectural scene, differences in depth are resolved to about 0.001 of the distance from camera to subject.

Technique for automated recognition of sunspots on full-disk solar images

A new robust technique is presented for automated identification of sunspots on full-disk white-light (WL) solar images obtained from SOHO/MDI instrument and Ca II K1 line images from the Meudon Observatory. Edge-detection methods are applied to find sunspot candidates followed by local thresholding using statistical properties of the region around sunspots. Possible initial oversegmentation of images is remedied with a median filter. The features are smoothed by using morphological closing operations and filled by applying watershed, followed by dilation operator to define regions of interest containing sunspots. A number of physical and geometrical parameters of detected sunspot features are extracted and stored in a relational database along with umbra-penumbra information in the form of pixel run-length data within a bounding rectangle. The detection results reveal very good agreement with the manual synoptic maps and a very high correlation with those produced manually by NOAA Observatory, USA.