International Journal of Scientific and Research Publications, Volume 6, Issue 7, July 2016 168 ISSN 2250-3153 www.ijsrp.org A Review on various widely used shadow detection methods to identify a shadow from images Akmalbek Abdusalomov 1 ,Taeg Keun Whangbo 2 , Oybek Djuraev 3 1 Department of Computer Engineering, Gachon University, 1342 Seongnamdaero, Sujeong-gu, Seongnam-si, Gyeonggi-do, 461-701, Korea akmalbekabdusalomov@gmail.com 2 Department of Computer Engineering, Gachon University, tkwhangbo@gachon.ac.kr 3 Department of Information Technologies, Tashkent University of Information Technologies, Uzbekistan odjuraev@gmail.com Abstract- In this paper, we address the different shadow detection methods and algorithms for both still and moving images as well as give a brief description of the advantages and disadvantages of each method. Shadow detection and removal is an important step in visual surveillance and monitoring systems. Shadow points are often misclassified as object points causing errors on localization, segmentation and classification of objects. Many algorithms and methods have been developed for different environmental conditions to detect shadow from the images. We will review some widely used methods how to detect shadows and extract it avoiding loss of texture information. Index Terms- Shadow detection, Shadow removal, Image processing, Intensity, Texture; I. INTRODUCTION hadow detection is becoming an active and attractive research area for many image processing applications such as traffic surveillance, object recognition and image segmentation. Shadows can cause objects merging, shapes distortion and object loss. Shadow distorts the object’s shape, so that the use of shape recognition techniques became not reliable (shadows and objects are merged in a single blob). In addition, shadow maybe classified as a totally erroneous object in the scene [1]. For these reasons, a simple, reliable and accurate method in shadows identification is required. In our survey, we study the more prominent shadow detection methods published during the last decade and show the strengths and weaknesses of each method. General concepts of shadow: What is a shadow? A shadow happens when an object partially or totally occluded by direct light from a source of illumination. Shadows often degrade the visual quality of images. Shadows can be divided two types: self and cast shadows. A self shadow occurs in the portion of an object which is not illuminated by direct light. A cast shadow is the area projected by the object in the direction of direct light [2]. Self shadow and cast shadow are shown in fig.1. Self and cast shadows produce different brightness values. Self shadows (also called attached shadows) usually have a higher brightness than cast shadows since they receive more secondary lighting from surrounding illumination objects. [3]. In addition, self-shadows are vague shadows and do not have clear boundaries. However, cast shadows are hard shadows and always have a violent contrast to background Fig.1 Shadow is divided as self and cast shadows Based on the intensity, cast shadow can be further divided into umbra (hard) and penumbra (soft) region, as depicted in fig.2. The soft shadows retain the texture of the background surface, whereas the hard shadows are too dark and have little S