An Evaluation of HMM-Based Techniques for the Recognition of Screen Rendered Text

Segmentation and recognition of screen rendered text is a challenging task due to its low resolution (72 or 96 ppi) and use of antialiased rendering. This paper evaluates Hidden Markov Model (HMM) techniques for OCR of low resolution text -- both on screen rendered isolated characters and screen rendered text-lines -- and compares it with the performance of other commercial and open source OCR systems. Results show that HMM-based methods reach the performance of other methods on screen rendered text and yield above 98% character level accuracies on both screen rendered text-lines and characters.