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The Luminance Misattribution in Lightness Perception  [PDF]
Alessandro Soranzo,Alessandra Galmonte,Tiziano Agostini
Psihologija , 2010,
Abstract: The Simultaneous Lightness Contrast is the condition whereby a grey patch on a dark background appears lighter than a physically identical patch on a light background. This is probably the most studied phenomenon in lightness perception. Although this phenomenon has been explained in terms of low-level mechanisms, convincing evidences supporting a high-level interpretation have been presented over the last decades. Two are the main highlevel interpretations. On one side, the layer approach claims that the visual system splits the luminance into separate overlapping layers, corresponding to separate physical contributions; whilst on the other side, the framework approach maintains that the visual system groups the luminance within a set of contiguous frameworks. One of the biggest weaknesses of the layer approach is that it cannot account properly for errors in lightness perception (Gilchrist, 2005 Current Biology, 15(9), 330–332). To extend the multiple layers interpretation to errors in lightness perception, in this study we show that the perceptual lightness difference among equal patches on different backgrounds increases even when the luminance contrast with their backgrounds shrinks. Specifically, it is shown that the perceptual lightness difference among equal patches on different backgrounds intensifies when a small-sized semi-transparent surface is interposed between the patches and the backgrounds. This result indicates that in these conditions the visual system besides decomposing the luminance into separate layers also becomes liable for a luminance misattribution. It is proposed that the photometric and geometric relationships among the luminance edges in the image might account for this misattribution.
Retinal Image Preprocessing: Background and Noise Segmentation
Usman Akram
TELKOMNIKA : Indonesian Journal of Electrical Engineering , 2012, DOI: 10.11591/telkomnika.v10i3.615
Abstract: Retinal images are used for the automated screening and diagnosis of diabetic retinopathy. The retinal image quality must be improved for the detection of features and abnormalities and for this purpose preprocessing of retinal images is vital. In this paper, we present a novel automated approach for preprocessing of colored retinal images. The proposed technique improves the quality of input retinal image by separating the background and noisy area from the overall image. It contains coarse segmentation and fine segmentation. Standard retinal images databases Diaretdb0, Diaretdb1, DRIVE and STARE are used to test the validation of our preprocessing technique. The experimental results show the validity of proposed preprocessing technique.
Lightness Perception Model for Natural Images  [PDF]
Xianglin Meng, Zhengzhi Wang
Journal of Software Engineering and Applications (JSEA) , 2010, DOI: 10.4236/jsea.2010.37079
Abstract: A perceptual lightness anchoring model based on visual cognition is proposed. It can recover absolute lightness of natural images using filling-in mechanism from single-scale boundaries. First, it adapts the response of retinal photoreceptors to varying levels of illumination. Then luminance-correlated contrast information can be obtained through multiplex encoding without additional luminance channel. Dynamic normalization is used to get smooth and continuous boundary contours. Different boundaries are used for ON and OFF channel diffusion layers. Theoretical analysis and simulation results indicate that the model could recover natural images under varying illumination, and solve the trapping, blurring and fogging problems to some extent.
Limits of Preprocessing  [PDF]
Stefan Szeider
Computer Science , 2011,
Abstract: We present a first theoretical analysis of the power of polynomial-time preprocessing for important combinatorial problems from various areas in AI. We consider problems from Constraint Satisfaction, Global Constraints, Satisfiability, Nonmonotonic and Bayesian Reasoning. We show that, subject to a complexity theoretic assumption, none of the considered problems can be reduced by polynomial-time preprocessing to a problem kernel whose size is polynomial in a structural problem parameter of the input, such as induced width or backdoor size. Our results provide a firm theoretical boundary for the performance of polynomial-time preprocessing algorithms for the considered problems.
Complex Vacuum and Lightness of Higgs Boson  [PDF]
Shou-hua Zhu
Physics , 2012,
Abstract: The CP violation observed in K- and B-mesons can be successfully accommodated via the CKM matrix in the standard model. However the additional CP violation is required in order to induce the matter and anti-matter asymmetry observed in the Universe. The additional CP violation can be induced by complex vacuum, namely the spontaneous CP violation. In this paper we reveal the intimate connection of the spontaneous CP violation and the lightness of the Higgs boson, which was recently discovered by ATLAS and CMS at the LHC.
The Professional Medical Journal , 2010,
Abstract: Objective: Evaluating circulating leukocytes in acute mental stress & relation with coronary artery disease. Design: Descriptive study Setting: Muhammad Medical College Mirpurkhas, Duration: from March 2007 to August 2007. Methods: Two hundred young healthy adults were studied for stress experiment. Venous blood samples were drawn before and after stress for estimation of leukocyte counts. Valueswere presented as mean ±standard error of mean (SEM). Results: The difference in Pre and during stress results of variables were TLC = -4630.85 ± 140.65, N % = -11.8 ± 0.36, L% = 4.03 ± 0.14, M %= 5.48 ± 0.37, E % = 1.18 ± 0.07, B % = 1.11 ± 0.022. Highly significant p-values (≤ 0.001) were found among various parameters, in both groups of subjects. Conclusion: An increase in the number of circulating leukocytes was an important unexpected observation that was noted. We suggest that the real life stress induced leukocytes changes may warrant further investigation about its relation with the coronary artery disease (CAD).
On lightness of one class of mappings in metric spaces  [PDF]
Evgeny Sevost'yanov,Sergei Skvortsov
Mathematics , 2015,
Abstract: For mappings in metric spaces satisfying one inequality with respect to modulus of families of curves, there is proved a lightness of preimage under the mapping. It is proved that, the mappings, satisfying estimate mentioned above, are light, whenever a function which corresponds to distortion of families of curves under the mapping, is of finite mean oscillation at every point.
The separating gonality of a separating real curve  [PDF]
Marc Coppens
Mathematics , 2011,
Abstract: A smooth real curve is called separating in case the complement of the real locus inside the complex locus is disconnected. This is the case if there exists a morphism to the projective line whose inverse image of the real locus of the projective line is the real locus of the curve. Such morphism is called a separating morphism. The minimal degree of a separating morphism is called the separating gonality. The separating gonality cannot be less than the number s of the connected components of the real locus of the curve. A theorem of Ahlfors implies this separating gonality is at most the g+1 with g the genus of the curve. A better upper bound depending on s is proved by Gabard. In this paper we prove that there are no more restrictions on the values of the separating gonality.
On QBF Proofs and Preprocessing  [PDF]
Mikolas Janota,Radu Grigore,Joao Marques-Silva
Computer Science , 2013,
Abstract: QBFs (quantified boolean formulas), which are a superset of propositional formulas, provide a canonical representation for PSPACE problems. To overcome the inherent complexity of QBF, significant effort has been invested in developing QBF solvers as well as the underlying proof systems. At the same time, formula preprocessing is crucial for the application of QBF solvers. This paper focuses on a missing link in currently-available technology: How to obtain a certificate (e.g. proof) for a formula that had been preprocessed before it was given to a solver? The paper targets a suite of commonly-used preprocessing techniques and shows how to reconstruct certificates for them. On the negative side, the paper discusses certain limitations of the currently-used proof systems in the light of preprocessing. The presented techniques were implemented and evaluated in the state-of-the-art QBF preprocessor bloqqer.
On Separating Families of Bipartitions  [PDF]
Takahisa Toda,Ivo Vigan
Mathematics , 2011,
Abstract: In this paper, we focus on families of bipartitions, i.e. set partitions consisting of at most two components. We say that a family of bipartitions is a separating family for a set $S$ if every two elements in $S$ can be separated by some bipartition. Furthermore, we call a separating family minimal if no proper subfamily is a separating family. We characterize the set of all minimal separating families of maximum size for arbitrary set $S$ as the set of all spanning trees on $S$ and enumerate minimal separating families of maximum size. Furthermore, we enumerate separating families of arbitrary size, which need not be minimal.
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