Topic

# Illumination problem

About: Illumination problem is a research topic. Over the lifetime, 93 publications have been published within this topic receiving 5859 citations.

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08 Jan 2021TL;DR: In this paper, background modelling of Geometric Mean (GM) based lognormal distribution of each pixel is considered, followed by K-mean clustering algorithm is used to separate background from foreground.

Abstract: Background Subtraction is widely used for detection of moving object, traffic management, and video surveillance even when the environmental condition is not favourable such as illumination problem, weather condition and fast moving object. Background subtraction methodology is extensively utilized in the detection of moving entity which is captured through a camera. Foundation for this methodology to identify the moving entity by observing the variation among the input frame and reference frame is described as background image. Fundamentally, background image is an illustration of section of images with no moving entity and that should be consistently modified to adjust with the changing illumination and geometric adjustments. Further composite prototypes were stretched the perception of background subtraction within the accurate significance. In this research, background modelling of Geometric Mean (GM) based lognormal distribution of each pixel is considered, followed by K-mean clustering algorithm is used to separate background from foreground. Finally to enhance the result weighted median filter is used. The proposed algorithm has been tested upon different data sets and the results shows better precision as compared to its ground truth by calculating sensitivity, specificity and accuracy.

1 citations

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09 Dec 2020TL;DR: Zhang et al. as discussed by the authors applied the Expected Patch Log Likelihood (EPLL) algorithm to extract illumination weight and combined it with the Neighboring Radiance Ratio (NRR) to optimize the initial vector of the Gaussian mixture model, which makes full use of the redundant information in images.

Abstract: Illumination is an important factor that impairs face recognition. Many algorithms have been proposed to solve the illumination problem. Most algorithms focus on one image information and only use local illumination change, to improve the effects of removing facial illumination. In this paper, we apply the Expected Patch Log Likelihood (EPLL) algorithm to extract illumination weight and we combine it with the Neighboring Radiance Ratio algorithm (NRR) to optimize the initial vector of the Gaussian mixture model, which makes full use of the redundant information in images. The experimental results on the extended Yale B and CMU PIE face databases show that the proposed algorithm can effectively eliminate the influence of illumination on face images and has a high robustness.

1 citations

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TL;DR: In this paper, a geometric shape of a reflector in terms of the optical path length to a receiving surface is represented by compact expressions, which are used to calculate the mapping between input rays and output rays, and differentiation of these expressions allows calculation of the illumination on the receiving surface.

Abstract: Compact expressions are presented to represent the geometric shape of a reflector in terms of the optical path length to a
receiving surface. These expressions are used to calculate the mapping between input rays and output rays, and
differentiation of these expressions allows calculation of the illumination on the receiving surface. The scalar value of an
optical path length, evaluated on an illuminated surface, is used as a basis to construct a potential function in three-space.
The value and gradient of this potential function are used to define a system of rays, and to solve for the mapping
between input rays and output rays. A result due to Oliker, concerning the existence of solutions to a near field
illumination problem, is discussed. This existence result is used in a continuity argument regarding the nature of the
mapping between input ray directions and incident points on a receiving plane. It is argued that the mapping from input
ray directions to incident points on a receiving plane is common to a family of reflectors that produce the same
illuminance distribution. Another mapping, describing the flow of illumination as a reflector is deformed, is also
discussed. A fluid mechanics analogy is explored, and a new method for reflector design is proposed.

1 citations

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01 Nov 2019

TL;DR: Genetic algorithm is used to explore exponential search space of lamps placement and find those that suit the given criteria and show promising arrangements of lamps that can be used in situations that require an emitter of signals in an obstruction filled environment.

Abstract: Illuminating rooms is something that is taken as for granted. This paper presents an evolutionary method for solving this problem. The paper aims to find a minimalist arrangement of lamps in user-defined or random rooms such that they are optimally lit. Genetic algorithm is used to explore exponential search space of lamps placement and find those that suit the given criteria. Blender is used as a 3-D tool for this experiment. Results show promising arrangements of lamps that can be used in situations that require an emitter of signals in an obstruction filled environment.

1 citations

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01 Nov 2013

TL;DR: Two proposals which improve the conventional Weberface in specific ways and derive an oriented Weberface and largely-scaled Weberfaces, aimed at better face representations which are capable of suppressing the illumination influence while maintaining useful facial features.

Abstract: Automatic face recognition under varying illumination is a challenging task. Numerous illumination insensitive face representation methods were developed to tackle the illumination problem. Weberface has been recently proposed and its robustness to varying illumination was approved both theoretically and experimentally. In this paper, we present two proposals which improve the conventional Weberface in specific ways and derive an oriented Weberface and largely-scaled Weberfaces. The oriented Weberface takes advantages of the detailed information along various directions within the neighbourhood of a pixel. It concatenates eight directional face images calculated according to the Weber’s law. The largely-scaled Weberfaces are created based on the fact that the “local” operation in illumination insensitive feature extraction does not necessarily correspond to the “nearest” neighborhood. It computes the facical features at larger scales than the conventional Weberface. These modifications are aimed at better face representations which are capable of suppressing the illumination influence while maintaining useful facial features. Through the experiments on three databases, we demonstrate large performance improvements (in terms of recognition rates) by the proposed methods, compared with the conventional Weberface. Our methods also yield better results than several state-of-the-art methods.

1 citations