Image Noise Parameter Estimation by Principal Component Analysis

Noise parameter estimation is an important image processing step, because the noise parameters are often unknown, but many image denoising, compression, and segmentation algorithms take them as input values. The innovation of this thesis is the introduction of a new noise parameter estimation framework. The framework is designed to handle images with signal-independent noise as well as several common types of signal-dependent noise, namely, noise produced by synthetic aperture radars (SAR), magnetic resonance imaging (MRI) devices, charge-coupled device (CCD) sensors, and ultrasound devices. The framework is based on a sparse representation of the blocks of the original image. Specifically, it is assumed that a part of the original image blocks lies in a proper subspace of the image block vector space, which means that there is a linear dependence between pixels in the blocks. As a result, images without homogeneous areas can be accurately processed, which is a qualitative difference from the state of the art, where homogeneous areas are required to process images with signal-dependent noise with several parameters. In the case of signal-independent noise, principal component analysis of the blocks of the input image is utilized in order to check the sparsity assumption and estimate the noise variance. Particularly, Bartlett's test and the difference of the sample covariance matrix eigenvalues are used as assumption checks, and the last several sample covariance matrix eigenvalues are utilized to estimate the noise variance. Besides, two strategies to select the part of the blocks, which allows the sparse representation, are suggested. In order to process images with signal-dependent noise, a variance-stabilizing transformation is applied. An optimization procedure is used to compute the transformation parameters, because they depend on the unknown noise parameters. This procedure analyzes the noise distribution in the transformed image and selects the transformation parameters, which maximize a noise normality measure. After applying the variance-stabilizing transformation, the algorithm designed for signal-independent noise is utilized to estimate the noise variance in the transformed image; and the parameters of the original noise model are calculated. The noise parameter estimation experiments, which include comparison with 19 state of the art methods, show that the accuracy of the proposed algorithms is the highest in most cases. Speaking of signal-independent noise, the proposed algorithm gives a good compromise between accuracy and execution time: it is at least 15 times faster compared with the methods with similar accuracy; and it is at least 2 times more accurate than other methods. Regarding signal-dependent noise, the accuracy of the proposed approach is considerably higher for the SAR, CCD, and ultrasound noise models. The denoising experiments demonstrate that the use of noise parameter estimates computed by the proposed method results in considerably higher denoising quality for these three noise models

MRI noise estimation and denoising using non-local PCA

NOTICE: this is the author’s version of a work that was accepted for publication in Medical Image AnalysisChanges resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Medical Image Analysis, [Volume 22, Issue 1, May 2015, Pages 35–47] DOI 10.1016/j.media.2015.01.004This paper proposes a novel method for MRI denoising that exploits both the sparseness and self-similarity properties of the MR images. The proposed method is a two-stage approach that first filters the noisy image using a non local PCA thresholding strategy by automatically estimating the local noise level present in the image and second uses this filtered image as a guide image within a rotationally invariant non-local means filter. The proposed method internally estimates the amount of local noise presents in the images that enables applying it automatically to images with spatially varying noise levels and also corrects the Rician noise induced bias locally. The proposed approach has been compared with related state-of-the-art methods showing competitive results in all the studied cases.We are grateful to Dr. Matteo Mangioni and Dr. Alessandro Foi for their help on running their BM4D method in our comparisons. We want also to thank Dr. Luis Marti-Bonmati and Dr. Angel Alberich-Bayarri from Quiron Hospital of Valencia for providing the real clinical data used in this paper. This study has been carried out with financial support from the French State, managed by the French National Research Agency (ANR) in the frame of the Investments for the future Programme IdEx Bordeaux (ANR-10-IDEX-03-02), Cluster of excellence CPU and TRAIL (HR-DTI ANR-10-LABX-57).Manjón Herrera, JV.; Coupé, P.; Buades, A. (2015). MRI noise estimation and denoising using non-local PCA. Medical Image Analysis. 22(1):35-47. doi:10.1016/j.media.2015.01.004S354722

Comparative Studies of the Left- and Right-Handed Peoples Temperament

The paper deals with the comparative analysis of the left and right-handed people's temperament. The research is based on the concept of the functional asymmetry responsible for the specificity of psychic reactions and resulting individual differences of those reactions in the groups of the left- and right-handed participants. The research subject embraces the differentiating features of the three personal traits: psychoticism, neuroticism and extraversion. The methodology tools combine the Hand Index experimental technique designed by the author along with the EPQ test by G. Eysenck. In the process of group formation, the hereditary impact of left-handedness was analyzed. It was proved that the participants with the left-handed relatives existence (so-called genetically lefties) are even more psychotic than the ones without such a heredity. They tend to higher lability of the nervous system and related emotional instability, unsteadiness and increased sensitivity, which are the common characteristic features of the left-handed people's temperament. All the left-handed participants proved to be more neurotic in comparison with the right-handed ones. The group differences concerning the extraversion/introversion scale were not statistically corroborated. The research results can be taken into account in differential psychology while investigating the temperament of the left-handed people.В статье рассмотрены результаты проведенного автором сравнительного исследования темперамента взрослых правшей и левшей. Сопоставление основывалось на том, что функциональная асимметрия мозга обусловливает своеобразие протекания психических процессов и может быть одной из важных причин выявленных психологами индивидуальных различий между людьми с разным характером наследственной мануальности. Предметом изучения стали отличительные особенности трех личностных измерений испытуемых - психотизма, нейротизма, экстраверсии. В качестве методического инструментария использовались созданная автором экспериментальная методика Индекс руки и Опросник EPQ Г. Айзенка. При формировании экспериментальных групп учитывались причины возникновения леворукости. Было установлено, что левши с наследственно обусловленной леворукостью более психотичны по сравнению с теми, леворукость которых в родословной четко не прослеживается. У представителей этой группы также наиболее отчетливо выражены лабильность нервной системы и связанные с ней эмоциональная неустойчивость, изменчивость, повышенная чувствительность, являющиеся фундаментальными свойствами темперамента левшей в целом. Все испытуемые-левши оказались более нейротичными по сравнению с правшами. Не выявлено различий между всеми группами по шкале экстраверсия / интроверсия . Результаты исследования могут быть учтены в ходе дальнейшей разработки проблемы темперамента левшей в дифференциальной психологии

Remote outcomes of treating patients with early forms of pelvic prolapse

The objective. Assessment of remote outcomes of various kinds of treatment in patients with early forms of pelvic prolapse. Patients and methods. We examined 240 women aged 28 to 42 years with pelvic prolapse (PP) stage 1-2 according to POP-Q assessment. Two groups of patients were singled out. Patients of group 1 (140) underwent surgical treatment (colpoperineorrhaphy, perineal levatorplasty), patients of group 2 (100) received conservative treatment that included instrumental therapies and home exercises. Remote outcomes of surgical and conservative treatments were assessed 5 years after treatment and included analysis of the patients' complaints and recovery of normal anatomical correlations at clinical examination, functional tests and echography. Results. A positive effect (lower stage of prolapse) was noted in 128 (91.4%) patients of the operative treatment group, and progression of prolapse - only in 1.5% of cases. Stabilisation of the process was found in 7.1% of the examined patients. In group 2, a positive effect was noted only in 4 patients (4%), and almost in every second patient prolapse progressed to more severe stages. Conclusion. Conservative treatment of patients has little effect, and in every third patient diseases progresses to more severe forms. Surgical treatment of early forms of PP is pathogenetically justified and highly effective, since it promotes recovery of the normal anatomy of the pelvic floor

Remote outcomes of treating patients with early forms of pelvic prolapse

The objective. Assessment of remote outcomes of various kinds of treatment in patients with early forms of pelvic prolapse. Patients and methods. We examined 240 women aged 28 to 42 years with pelvic prolapse (PP) stage 1-2 according to POP-Q assessment. Two groups of patients were singled out. Patients of group 1 (140) underwent surgical treatment (colpoperineorrhaphy, perineal levatorplasty), patients of group 2 (100) received conservative treatment that included instrumental therapies and home exercises. Remote outcomes of surgical and conservative treatments were assessed 5 years after treatment and included analysis of the patients' complaints and recovery of normal anatomical correlations at clinical examination, functional tests and echography. Results. A positive effect (lower stage of prolapse) was noted in 128 (91.4%) patients of the operative treatment group, and progression of prolapse - only in 1.5% of cases. Stabilisation of the process was found in 7.1% of the examined patients. In group 2, a positive effect was noted only in 4 patients (4%), and almost in every second patient prolapse progressed to more severe stages. Conclusion. Conservative treatment of patients has little effect, and in every third patient diseases progresses to more severe forms. Surgical treatment of early forms of PP is pathogenetically justified and highly effective, since it promotes recovery of the normal anatomy of the pelvic floor

Self-oscillation suppression when turning non-rigid shafts using spring tools and the spring headstock center

One of the new but understudied self-oscillation elimination methods applied in metal cutting involves creation of an extra tangential oscillating circuit adjusted to resonance with the main normal circuit in the cutting zone. To assess the efficiency of the method, spring tool and driving dogs were developed. They were used in axial turning of non-rigid shafts. In comparison with standard tools fastened in the center, spring tools decrease the amplitude of self-oscillations by a mean of 90 %

Correlation Between Left/Right-Handedness and Thinking

В статье приведены результаты исследования возможной взаимосвязи между моторной асимметрией и индивидуальными стилями мышления как внутренней результирующей внешнего опыта человека. Подтвердились гипотезы о том, что показатель «индекс руки» положительно связан с аналитическим и отрицательно - с прагматическим стилем мышления; а также о том, что праворукие студенты предпочитают использовать аналитический стиль мышления. На уровне тенденции было установлено, что 31% студентов, не имеющих родственников левшей, предпочитают использовать аналитический стиль мышления. Из тех, кто имеет таких родственников, 32% предпочитают идеалистический стиль, а 27% - реалистический стиль мышления.The paper outlines the research data of correlation between the hand prevalence and thinking, proving the hypothesis that the Index of the Left/Right-handedness correlates with individual thinking,namely the right-handed group has a correlation-plus with analytical thinking, while the left-handed group has a correlation-plus with pragmatic thinking. The research also shows that the students having no left-handed relatives tend to demonstrate analytic thinking (31% of the students),whereas those having such relatives tend to idealistic thinking (32% of a students) and realistic thinking (27% of the students)

Ovarian reserve and endometrioid ovarian cysts: Clinical and ultrasound aspects

The objective. To study laparoscopic values and establish specificities of endometrioid ovarian cysts and Doppler parameters in healthy ovarian tissue containing an endometrioid cyst in infertile patients with low and normal ovarian reserve. Patients and methods. We examined 100 patients of reproductive age with primary infertility and endometrioid ovarian cysts. Depending on the state of ovarian reserve, 2 groups were singled out: Group 1 comprised patients with low ovarian reserve (n = 55) (anti-Müllerian hormone level (AMH) less than 2.0 ng/ml, follicle-stimulating hormone (FSH ΦCT) higher than 10 IU/l), group 2 - patients (n = 45) with normal ovarian reserve (AMH level higher than 2.0 ng/ml, FSH less than 8 IU/l). Before and after surgery, 2D- and 3D-transvaginal ultrasound was used in grey-scale, colour and power Doppler modes. 3D-angiography was used to assess vascularisation of ovarian tissue. Results. In the group of patients with low ovarian reserve, in case of cyst location in the area of the infundibulopelvic and proper ovarian ligament vascularisation and perfusion of normal ovarian tissue were significantly lower as compared to «marginal» location of the cyst in the same group (VI - 0.62 ± 0.16%, FI - 18.11 ± 2.53, PI - 1.77 ± 0.14, RI - 0.72 ± 0.05 and VI - 0.81 ± 0.57%, FI - 25.7 ± 2.53%, PI - 1.56 ± 0.11, RI - 0.65 ± 0.04, respectively). In patients with normal ovarian reserve, intraovarian blood flow in the affected ovary was damaged insignificantly. Conclusion. The presence of an endometrioid cyst is not always associated with damage to ovarian reserve: If the cyst size is more than 5 cm the possibility of damage to ovarian reserve increases by 3.5 times; if cyst sizes are 3-5 cm ovarian reserve might be both low and high. Influence of endometrioid cysts on ovarian reserve is conditioned by their size, location, characteristics of the capsule and spread of extragenital endometriosis