The built-in cameras and powerful processors have turned smartphones into 
ubiquitous barcode scanners. In smartphone-based barcode scanning, barcode 
localization is an important preprocessing step that quickly scans the entire 
camera image and passes barcode candidates to the actual decoder. This paper 
presents the implementation steps of a robust joint 1D and 2D barcode 
localization algorithm on the mobile GPU. The barcode probability maps are 
derived from the structure matrix and the color of the individual pixels. The 
different steps of the localization algorithm are formulated as OpenGL ES 2.0 
fragment shaders and both 1D and 2D barcode saliency maps are computed 
directly on the graphics hardware. The presented method can detect barcodes at 
various scales and orientations at 6 frames per second in HD resolution images 
on current generation smartphones.