Text Recognition in Natural Images Using Multiclass Hough Forests

Text detection and recognition in natural images are popular yet unsolved problems in computer vision. In this paper, we propose a technique that attempts to detect and recognize text in a unified manner by searching for words directly without reducing the image into text regions or individual characters. We present three contributions. First, we modify an object detection framework called Hough Forests (Gall et al., 2011) by introducing "Cross-Scale Binary Features" that compares the information between the same image patch at different scales. We use this modified technique to produce likelihood maps for every text character. Second, our word-formation cost function and computed likelihood maps are used to detect and recognize the text in natural images. We test our technique with the Street View House Numbers (Netzer et al., 2011) and the ICDAR 2003 (Lucas et al., 2003) datasets. For the SVHN dataset, our algorithm outperforms recent methods and has comparable performance using fewer training samples. We also exceed the state-of-the-art word recognition performance for ICDAR 2003 dataset by 4%. Our final contribution is a realistic dataset generation code for text characters.