Reading 1-D Barcodes with Mobile Phones Using Deformable Templates

Camera cellphones have become ubiquitous, thus opening a plethora of opportunities for mobile vision applications. For instance, they can enable users to access reviews or price comparisons for a product from a picture of its barcode while still in the store. Barcode reading needs to be robust to challenging conditions such as blur, noise, low resolution, or low quality camera lenses, all of which are extremely common. Surprisingly, even state-of-the-art barcode reading algorithms fail when some of these factors come into play. One reason resides in the early-commitment strategy that virtually all existing algorithms adopt: the image is first binarized and then only the binary data is processed. We propose a new approach to barcode decoding that bypasses binarization. Our technique relies on deformable templates and exploits all the gray level information of each pixel. Due to our parametrization of these templates, we can efficiently perform maximum likelihood estimation independently on each digit and enforce spatial coherence in a subsequent step. We show by way of experiments on challenging UPC-A barcode images from five different databases that our approach outperforms competing algorithms. Implemented on a Nokia N95 phone, our algorithm can localize and decode a barcode on a VGA image (640×480, JPEG compressed) in an average time of 400–500 ms.