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Cast shadows add additional difficulties on detecting objects because they locally modify image intensity and color. Shadows may appear or disappear in an image when the object, the camera, or both are free to move through a scene. This work evaluates the performance of an object detection method based on boosted HOG paired with three different image representations in outdoor video sequences. We...
We developed a two-shot 6-band image capturing system consisting of a large-format camera, a customized interference filter, and a scanning digital back to capture a 185-M-pixel images. The interference filter is set in front of the camera lens to obtain a 6-band image, that is, two 3-band images, one taken with the filter and the other without it. After correction of optical aberrations caused by...
The Local Binary Pattern (LBP) operator is a computationally efficient yet powerful feature for analyzing local texture structures. While the LBP operator has been successfully applied to tasks as diverse as texture classification, texture segmentation, face recognition and facial expression recognition, etc., it has been rarely used in the domain of Visual Object Classes (VOC) recognition mainly...
Moving cast shadow removal is an important yet difficult problem in video analysis and applications. This paper presents a novel algorithm for detection of moving cast shadows, that based on a local texture descriptor called Scale Invariant Local Ternary Pattern (SILTP). An assumption is made that the texture properties of cast shadows bears similar patterns to those of the background beneath them...
In this paper, we propose a framework for isolating text regions from natural scene images. The main algorithm has two functions: it generates text region candidates, and it verifies of the label of the candidates (text or non-text). The text region candidates are generated through a modified K-means clustering algorithm, which references texture features, edge information and color information. The...
A visual appearance of natural materials fundamentally depends on illumination conditions, which significantly complicates a real scene analysis. We propose textural features based on fast Markovian statistics, which are simultaneously invariant to illumination colour and robust to illumination direction. No knowledge of illumination conditions is required and a recognition is possible from a single...
This paper presents an automatic face replacement approach in video based on 2D morphable model. Our approach includes three main modules: face alignment, face morph, and face fusion. Given a source image and target video, the Active Shape Models (ASM) is adopted to source image and target frames for face alignment. Then the source face shape is warped to match the target face shape by a 2D morphable...
We address the problem of multiple people tracking under non-homogenous and time-varying illumination conditions. We propose a unified framework for jointly estimating the position of the targets and their illumination conditions. For each target multiple templates are considered to model appearance variations due to lighting changes. The template choice is driven by an illumination map which describes...
Illumination-robust optical flow algorithms are needed in numerous machine vision applications such as vision-based intelligent vehicles, surveillance and traffic monitoring. Recently, we have proposed an implicit nonlinear scheme for variational optical flow that assumes no particular analytical form of energy functional and can accommodate various image components and data metrics. Using test data...
We address here the problem of color constancy and propose a new method to achieve color constancy based on the statistics of images with color cast. Images with color cast have standard deviation of one color channel significantly different from that of other color channels. This observation is also applicable to local patches of images and ratio of the maximum and minimum standard deviation of color...
The output from a color imaging sensor, or apparent color, can change considerably due to illumination conditions and scene geometry changes. In this work we take into account the dependence of apparent color with illumination an attempt to find appropriate color models for the typical conditions found in outdoor settings. We evaluate three color based trackers, one based on hue, another based on...
In this paper, we present a new solution to the problem of matching groups of people across multiple non-overlapping cameras. Similar to the problem of matching individuals across cameras, matching groups of people also faces challenges such as variations of illumination conditions, poses and camera parameters. Moreover, people often swap their positions while walking in a group. In this paper, we...
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