Color Image Clustering using Block Truncation Algorithm

With the advancement in image capturing device, the image data been generated at high volume. If images are analyzed properly, they can reveal useful information to the human users. Content based image retrieval address the problem of retrieving images relevant to the user needs from image databases on the basis of low-level visual features that can be derived from the images. Grouping images into meaningful categories to reveal useful information is a challenging and important problem. Clustering is a data mining technique to group a set of unsupervised data based on the conceptual clustering principal: maximizing the intraclass similarity and minimizing the interclass similarity. Proposed framework focuses on color as feature. Color Moment and Block Truncation Coding (BTC) are used to extract features for image dataset. Experimental study using K-Means clustering algorithm is conducted to group the image dataset into various clusters

Automatically Repairing Programs Using Both Tests and Bug Reports

The success of automated program repair (APR) depends significantly on its ability to localize the defects it is repairing. For fault localization (FL), APR tools typically use either spectrum-based (SBFL) techniques that use test executions or information-retrieval-based (IRFL) techniques that use bug reports. These two approaches often complement each other, patching different defects. No existing repair tool uses both SBFL and IRFL. We develop RAFL (Rank-Aggregation-Based Fault Localization), a novel FL approach that combines multiple FL techniques. We also develop Blues, a new IRFL technique that uses bug reports, and an unsupervised approach to localize defects. On a dataset of 818 real-world defects, SBIR (combined SBFL and Blues) consistently localizes more bugs and ranks buggy statements higher than the two underlying techniques. For example, SBIR correctly identifies a buggy statement as the most suspicious for 18.1% of the defects, while SBFL does so for 10.9% and Blues for 3.1%. We extend SimFix, a state-of-the-art APR tool, to use SBIR, SBFL, and Blues. SimFix using SBIR patches 112 out of the 818 defects; 110 when using SBFL, and 55 when using Blues. The 112 patched defects include 55 defects patched exclusively using SBFL, 7 patched exclusively using IRFL, 47 patched using both SBFL and IRFL and 3 new defects. SimFix using Blues significantly outperforms iFixR, the state-of-the-art IRFL-based APR tool. Overall, SimFix using our FL techniques patches ten defects no prior tools could patch. By evaluating on a benchmark of 818 defects, 442 previously unused in APR evaluations, we find that prior evaluations on the overused Defects4J benchmark have led to overly generous findings. Our paper is the first to (1) use combined FL for APR, (2) apply a more rigorous methodology for measuring patch correctness, and (3) evaluate on the new, substantially larger version of Defects4J.Comment: working pape

Highly accelerated cardiovascular magnetic resonance myocardial perfusion imaging: studies in spatial resolution, spatial coverage and cardiac phase

Background: Myocardial perfusion imaging with cardiovascular magnetic resonance (CMR) is bound by spatio-temporal constraints. Standard perfusion CMR techniques permit the acquisition of 3-4 myocardial slices with a spatial resolution of 2-3mm. However, acceleration techniques can be applied to achieve higher spatial resolution (<2mm) or 3-dimensional (3D) acquisitions with increased spatial coverage (12-16 slices). Acceleration can also be used to simultaneously acquire perfusion data at different time-points in the cardiac cycle. Accordingly, this thesis includes studies that modify the standard approach to perfusion CMR in order to investigate the impact of spatial resolution, spatial coverage and cardiac phase of acquisition. Methods and Results: Study 1 and 2 compared high-resolution and standard-resolution perfusion CMR in patients with suspected coronary artery disease (CAD). Study 1 found high-resolution acquisition had greater diagnostic accuracy compared to standard-resolution for detecting CAD (area under curve [AUC]: 0.93 vs. 0.83; p<0.001); and study 2 found it also had greater diagnostic accuracy for specifically identifying 3-vessel CAD (AUC: 0.90 vs. 0.69; p<0.0001). Study 3 compared high-resolution and 3D perfusion CMR in patients with CAD and found limited agreement between myocardial ischaemic burden estimates (95% limits of agreement: -8.68%, 9.82%). Study 4 and 5 compared systolic and diastolic acquisitions using standard perfusion CMR (limited to 1 slice) and 3D perfusion CMR respectively. Both studies found higher estimates of myocardial blood flow (MBF) in diastole compared to systole at stress (p<0.05). Study 6 utilised accelerated perfusion CMR to compare MBF estimates at 5 different time-points in the cardiac cycle in healthy volunteers. Estimates of stress MBF peaked at end-diastole and fell steadily to end-systole (p<0.0001). Conclusion: By altering the spatial resolution, spatial coverage and cardiac phase of acquisition of perfusion CMR, we have gained valuable insights into the relative impact of these parameters on both qualitative and quantitative assessment of ischaemia

Impact of incomplete ventricular coverage on diagnostic performance of myocardial perfusion imaging.

In the context of myocardial perfusion imaging (MPI) with cardiac magnetic resonance (CMR), there is ongoing debate on the merits of using technically complex acquisition methods to achieve whole-heart spatial coverage, rather than conventional 3-slice acquisition. An adequately powered comparative study is difficult to achieve given the requirement for two separate stress CMR studies in each patient. The aim of this work is to draw relevant conclusions from SPECT MPI by comparing whole-heart versus simulated 3-slice coverage in a large existing dataset. SPECT data from 651 patients with suspected coronary artery disease who underwent invasive angiography were analyzed. A computational approach was designed to model 3-slice MPI by retrospective subsampling of whole- heart data. For both whole-heart and 3-slice approaches, the diagnostic performance and the stress total perfusion deficit (TPD) score-a measure of ischemia extent/severity-were quantified and compared. Diagnostic accuracy for the 3-slice and whole-heart approaches were similar (area under the curve: 0.843 vs. 0.855, respectively; P = 0.07). The majority (54%) of cases missed by 3-slice imaging had primarily apical ischemia. Whole-heart and 3-slice TPD scores were strongly correlated (R2 = 0.93, P &lt; 0.001) but 3-slice TPD showed a small yet significant bias compared to whole-heart TPD (- 1.19%; P &lt; 0.0001) and the 95% limits of agreement were relatively wide (- 6.65% to 4.27%). Incomplete ventricular coverage typically acquired in 3-slice CMR MPI does not significantly affect the diagnostic accuracy. However, 3-slice MPI may fail to detect severe apical ischemia and underestimate the extent/severity of perfusion defects. Our results suggest that caution is required when comparing the ischemic burden between 3-slice and whole-heart datasets, and corroborate the need to establish prognostic thresholds specific to each approach