Text localization in web images using probabilistic candidate selection model

Abstract

Web has become increasingly oriented to multimedia content. Most information on the web is conveyed from images. Therefore, a new survey is conducted to investigate the relationship among text in web image, web image and web page. The survey result shows that it is a necessity to extract textual information in web images. Text localization in web image plays an important role in web image information extraction and retrieval. Current works on text localization in web images assume that text regions are in homogenous color and high contrast. Hence, the approaches may fail when text regions are in multi-color or imposed in complex background. In this thesis, we propose a text extraction algorithm from web images based on the probabilistic candidate selection model. The model firstly segments text region candidates from input images using wavelet, Gaussian mixture model (GMM) and triangulation. The likelihood of a candidate region containing text is then learnt using a Bayesian probabilistic model from two features, namely, histogram of oriented gradient (HOG) and local binary pattern histogram Fourier feature (LBP-HF). Finally best candidate regions are integrated to form text regions. The algorithm is evaluated using 365 non-homogenous web images containing around 800 text regions. The results show that the proposed model is able to extract text regions from non-homogenous images effectively.