Locating characters in scene images using frequency features

Abstract

This paper presents a (language-independent) method of locating rectangular text regions in natural scene images. The method consists of two steps that can be applied in succession or independently: the frequency of edge pixels across vertical and horizontal scan lines, and the fundamental frequency in the Fourier domain. The frequency feature of text images is highly intuitive, and this is the focus of the research. The detection of rectangles using a Hough transform is also addressed. Texts that are meaningful to many viewers usually appear in rectangles of colours of high contrast to the background. Hence it is natural to assume that the detection of rectangles may be helpful for locating desired texts correctly in natural outdoor scene images.