Image Enhancement with Statistical Estimation

Contrast enhancement is an important area of research for the image analysis. Over the decade, the researcher worked on this domain to develop an efficient and adequate algorithm. The proposed method will enhance the contrast of image using Binarization method with the help of Maximum Likelihood Estimation (MLE). The paper aims to enhance the image contrast of bimodal and multi-modal images. The proposed methodology use to collect mathematical information retrieves from the image. In this paper, we are using binarization method that generates the desired histogram by separating image nodes. It generates the enhanced image using histogram specification with binarization method. The proposed method has showed an improvement in the image contrast enhancement compare with the other image.Comment: 9 pages,6 figures; ISSN:0975-5578 (Online); 0975-5934 (Print

Image registration: Features and applications

Ph.DDOCTOR OF PHILOSOPH

Visual image processing in various representation spaces for documentary preservation

This thesis establishes an advanced image processing framework for the enhancement and restoration of historical document images (HDI) in both intensity (gray-scale or color) and multispectral (MS) representation spaces. It provides three major contributions: 1) the binarization of gray-scale HDI; 2) the visual quality restoration of MS HDI; and 3) automatic reference data (RD) estimation for HDI binarization. HDI binarization is one of the enhancement techniques that produces bi-level information which is easy to handle using methods of analysis (OCR, for instance) and is less computationally costly to process than 256 levels of grey or color images. Restoring the visual quality of HDI in an MS representation space enhances their legibility, which is not possible with conventional intensity-based restoration methods, and HDI legibility is the main concern of historians and librarians wishing to transfer knowledge and revive ancient cultural heritage. The use of MS imaging systems is a new and attractive research trend in the field of numerical processing of cultural heritage documents. In this thesis, these systems are also used for automatically estimating more accurate RD to be used for the evaluation of HDI binarization algorithms in order to track the level of human performance. Our first contribution, which is a new adaptive method of intensity-based binarization, is defined at the outset. Since degradation is present over document images, binarization methods must be adapted to handle degradation phenomena locally. Unfortunately, these methods are not effective, as they are not able to capture weak text strokes, which results in a deterioration of the performance of character recognition engines. The proposed approach first detects a subset of the most probable text pixels, which are used to locally estimate the parameters of the two classes of pixels (text and background), and then performs a simple maximum likelihood (ML) to locally classify the remaining pixels based on their class membership. To the best of our knowledge, this is the first time local parameter estimation and classification in an ML framework has been introduced for HDI binarization with promising results. A limitation of this method in the case with as the intensity-based methods of enhancement is that they are not effective in dealing with severely degraded HDI. Developing more advanced methods based on MS information would be a promising alternative avenue of research. In the second contribution, a novel approach to the visual restoration of HDI is defined. The approach is aimed at providing end users (historians, librarians, etc..) with better HDI visualization, specifically; it aims to restore them from degradations, while keeping the original appearance of the HDI intact. Practically, this problem cannot be solved by conventional intensity-based restoration methods. To cope with these limitations, MS imaging is used to produce additional spectral images in the invisible light (infrared and ultraviolet) range, which gives greater contrast to objects in the documents. The inpainting-based variational framework proposed here for HDI restoration involves isolating the degradation phenomena in the infrared spectral images, and then inpainting them in the visible spectral images. The final color image to visualize is therefore reconstructed from the restored visible spectral images. To the best of our knowledge, this is the first time the inpainting technique has been introduced for MS HDI. The experimental results are promising, and our objective, in collaboration with the BAnQ (Bibliothèque et Archives nationales de Québec), is to push heritage documents into the public domain and build an intelligent engine for accessing them. It is useful to note that the proposed model can be extended to other MS-based image processing tasks. Our third contribution is presented, which is to consider a new problem of RD (reference data) estimation, in order to show the importance of working with MS images rather than gray-scale or color images. RDs are mandatory for comparing different binarization algorithms, and they are usually generated by an expert. However, an expert’s RD is always subject to mislabeling and judgment errors, especially in the case of degraded data in restricted representation spaces (gray-scale or color images). In the proposed method, multiple RD generated by several experts are used in combination with MS HDI to estimate new, more accurate RD. The idea is to include the agreement of experts about labels and the multivariate data fidelity in a single Bayesian classification framework to estimate the a posteriori probability of new labels forming the final estimated RD. Our experiments show that estimated RD are more accurate than an expert’s RD. To the best of our knowledge, no similar work to combine binary data and multivariate data for the estimation of RD has been conducted

Cerebral oedema after reperfusion therapy in patients with ischaemic stroke : predictors, outcomes and treatment

Introduction: Reperfusion therapy by intravenous thrombolysis (IVT) and/or endovascular thrombectomy (EVT) are established treatments in ischaemic stroke. Cerebral oedema (COED), caused by dysfunction the blood brain barrier (BBB), is common early after acute ischaemic stroke (AIS), can aggravate the symptoms and worsen the prognosis. Data on predictors and the effect of recanalization on early COED is limited. A large infarction with COED involving the middle cerebral artery (MCA) can be life-threatening. Decompressive hemicraniectomy (DHC) reduces mortality and may have a positive effect on functional outcome in younger patients. Animal data suggest that imatinib, a tyrosine kinase inhibitor, may restore BBB integrity, thereby reducing haemorrhagic transformation (HT) and COED. The aim of this doctoral thesis was to contribute to the understanding of clinical aspects of COED in patients with AIS of the anterior circulation. Methods: Paper I, II and IV reported retrospective, observational studies using data from the Safe Implementations of Treatments in Stroke (SITS) International Stroke Registry, a prospective, multinational registry. These studies included patient data recorded using the SITS Registry data collection protocols for IVT and EVT, and to some extent general stroke, in time periods between 2002 and 2019. All patients had presumed ischaemic stroke. Paper III reported a phase 2, randomized, open-label, pilot study of imatinib in patients who received IVT after ischaemic stroke at 5 hospitals in Stockholm 2011-2014. All papers evaluated COED using the SITS COED scale (no, mild, moderate or severe COED). Outcomes at 3 months were functional outcome using the modified Rankin scale (mRS) score and death of any cause. Results: In paper I, the most important predictors of COED after AIS were assessed. Among 42 187 patients (median age 70 years), 12.5% had mild COED on follow-up imaging (22-36 hours or any extra investigation) and 10.2% had moderate or severe COED. Baseline National Institutes of Health Stroke Scale (NIHSS) score, followed by hyperdense artery sign (HAS), were the strongest predictors for COED. Additionally, higher blood glucose, impaired level of consciousness and imaging signs of early infarction at baseline were predictors for COED. Increasing degree of COED at 22-36 hours was associated with increasing mortality and worse functional outcome at 3 months. In paper II, the effect of recanalization on COED was assessed. Reperfusion therapy was administered to the 22 184 patients (median age 71 years and NIHSS score 16): only IVT (82.6%), IVT and EVT (13.8%) or only EVT (3.6%). Overall, recanalization was associated with a 10.6% (p<0.001) absolute risk reduction of moderate to severe COED at 22-36 hours, relative risk (RR) 0.55 (95% CI 0.52-0.58). Two models with high predictive ability provided the following estimates: adjusted OR 0.52 (95% CI, 0.46-0.59) and, with additional adjustment for parenchymal haemorrhage (PH), OR 0.46 (95% CI, 0.41-0.52). Moreover, recanalization was associated with a 13.6% (p<0.001) absolute reduction of mortality at 3 months, RR 0.58 (95% CI 0.55-0.61), adjusted OR 0.48 (95% CI 0.45-0.53). In paper III, 60 patients were randomized (15 patients in low-dose, 14 patients in medium and high-dose and 17 patients in control). Four serious adverse events (2 in control and 2 in low-dose group) resulted in the death of 3 patients. Of the dead patients 2 were allocated to low-dose group but of these, 1 did not receive imatinib and 1 patient had received only 2 doses. In the per protocol analysis, there were 21 haemorrhagic infarctions (6 in control), 3 PH (1 in control) and 4 remote parenchymal haemorrhages (0 in control). There were 33 cases of COED with moderate to severe COED being less frequent with higher doses, and no cases of moderate to severe COED in the high-dose group. After adjustment for EVT, the mean improvement in the NIHSS score compared to controls was 2 points (p=0.259) for the low-dose group, 3 points (p=0.106) for the medium-dose groups and 5 points (p=0.012) for the high-dose group. Functional independence (mRS 0-2) at 3 months was observed in 61% of the control group and 72% of all imatinib-treated patients; OR, adjusted for EVT, was 2.33 (95% CI 0.48-11.44). Paper IV reported anterior circulation AIS patients that underwent DHC. In 684 patients from 35 countries median age was 56 years and NIHSS score at baseline 18 and 98.1% received reperfusion therapy. Moderate to severe COED was detected in in 76.0% and PH in 25.8% at 22-36 hours follow-up imaging scans. Surgery-related details, for example timing of DHC, were not registered. Mortality at 3 months was 32.7% (159/486). Among baseline variables, only increasing age was independently associated with death (OR 1.06, 95% CI 1.03-1.08). Good outcome (mRS 0-3) at 3 months was observed in 13.9% (66/475) and mRS 0-4 was observed in 39.4% (187/475). Outcomes differed between patients aged ≤60 years ≥61 years (25.2% versus 47.8% for mortality and 16.6% versus 8.4% for good outcome). Right-sided involvement of vascular territory was more common than left-sided. Conclusions: The most important baseline predictors for early COED are NIHSS score, HAS, higher blood glucose, decreased level of consciousness, and signs of acute infarction at baseline. This finding can be used to improve selection and monitoring of patients for drug or surgical treatment. In patients with AIS, recanalization was associated with a lower risk for early COED even after adjustment for higher rate of PH in recanalized patients. Imatinib is safe and tolerable and may reduce neurological disability in patients treated with IVT after AIS. A confirmatory randomized trial is ongoing. DHC in routine clinical practice may have worse outcomes than randomized trials, although there are caveats due to short follow-up of the patients in this study. Right-sided arterial occlusions were more common than left-sided, which indicates a tendency to perform DHC in infarctions of the right hemisphere. In general, this doctoral thesis added new knowledge about several aspects of COED in AIS and a potential new pharmacological therapy for acute ischaemic stroke. Further research is required to confirm these results which are based on 3 retrospective observational studies and one phase 2 pilot study. In fact, an efficacy trial of imatinib is now ongoing

The feasibility of sports grips customisation using rapid manufacturing methodologies

In many sports where an implement is used to strike a ball, the grip is typically the sole point of contact between the player and implement. The grip significantly influences how a player wields an implement and is also a means for a player to experience impact forces and vibration. This transmission of force and vibration to the hand can affect a player's control, perception of the equipment, and also expose a player to injury or provoke degeneration of existing maladies. In general, the grip is the least expensive component of an implement. Little development over the previous two decades has been invested on the grip when compared to the vast changes in design, geometry and materials used in the implements which they are attached to. The development and flexibility of a group of manufacturing processes collectively known as rapid manufacturing have begun to introduce customised products to the mass-market. The main advantage of rapid manufacturing processes is the lack of tooling required, allowing parts to be produced directly from 3D CAD models using an expanding range of polymers and other materials. The integration of rapid manufactured parts into recreational sports equipment has not previously been attempted and is the focus of this work, with tennis selected as the candidate sport. [Continues.

Soundings: the Newsletter of the Monterey Bay Chapter of the American Cetacean Society. 2013

Issues January - November/December 2013. (PDF contains 96 pages

6th International Meeting on Retouching of Cultural Heritage, RECH6

RECH Biennial Meeting is one of the largest educational and scientific events in Retouching field, an ideal venue for conservators and scientists to present their research results about retouching. The main focus will be to promote the exchange of ideas, concepts, terminology, methods, techniques and materials applied during the retouching process in different areas of conservation: mural painting, easel painting, sculpture, graphic documentation, architecture, plasterwork, photography, contemporary art, among others. This Meeting aims to address retouching by encouraging papers that contribute to a deeper understanding of this final task of the conservation and restoration intervention. The main theme embraces the concepts of retouching, the criteria and limits in the retouching process, the bad retouching impact on heritage and their technical and scientific developments.This Meeting will discuss real-life approaches on retouching, focusing on practical solutions and on sharing experiencesColomina Subiela, A.; Doménech García, B.; Bailão, A. (2023). 6th International Meeting on Retouching of Cultural Heritage, RECH6. Editorial Universitat Politècnica de València. https://doi.org/10.4995/RECH6.2021.1601