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Localization and Segmentation of 2D High Capacity Color Barcodes. Devi Parikh Carnegie Mellon University. Gavin Jancke Microsoft Research, Redmond. Motivation. UPC Barcode. QR Code. Datamatrix. HCCB. Microsoft’s High Capacity Color Barcode. Application.
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Localization and Segmentation of 2D High Capacity Color Barcodes Devi Parikh Carnegie Mellon University Gavin Jancke Microsoft Research, Redmond
Motivation UPC Barcode QR Code Datamatrix
HCCB Microsoft’s High Capacity Color Barcode
Application Uniquely identifying commercial audiovisual works such as motion pictures, video games, broadcasts, digital video recordings and other media
Goal Locate and Segment the barcode from consumer images
Overview • Design specifications of Microsoft’s HCCB • Approach • Localization • Segmentation • Progressive Strategy • Results • Conclusions
Microsoft’s HCCB 4 or 8 colors Triangles String of colors palette
Microsoft’s HCCB Aspect ratio: r R rows S = (r+1)*R S symbols per row
Approach Thresholding Orientation prediction Barcode localization Corner localization Row localization Symbol localization Barcode segmentation Color assignments point inside the barcode is known
Localization: Thresholding • Identify thick white band and row separators • Normalization • Adaptive
Localization: Orientation summation distance -90 0 90 orientation orientation
Localization: Corners • Rough estimates whiteness mask non-texture mask combined mask
Localization: Corners • Gradient based refinement
Localization: Corners • Line based refinement
Segmentation: Rows Flip? Summation
S E Segmentation: Symbols Number of symbols per row q(S,E) = Sq(samples|S,E) Local search
Segmentation: Colors Palette
Observations • Segmentation results given accurate localization • Satisfactory • Corner localization • Unsatisfactory • No one strategy works well on all images • However (1) Errors of different strategies are complementary (2) Results are verifiable with decoder in the loop!
Progressive strategy • Hence – progressive strategy! • Similar to ensemble of weak classifiers • Or hypothesize-and-test • Multiple strategies: • Rough + gradient + line, or rough + line, or rough + gradient, or rough alone • Different values of threshold during rough corner detection • Total 12 • Order of strategies
Results • Dataset of 500 images • Performance metric: % barcodes successfully decoded • Decoder model: Barcode successfully decoded if 80% of symbols are correctly identified
Results Allows for explicit trade-off between accuracy and computational time
Conclusions • 2D High Capacity Color Barcode (HCCB) • Successful localization and segmentation of HCCB from consumer images • Varying densities, aspect ratios, lighting, color balance, image quality, etc. • Simple computer vision and image processing techniques • Progressive strategy
Acknowledgements Microsoft Research • Larry Zitnick • Andy Wilson • Zhengyou Zhang Carnegie Mellon University • Advisor: Tsuhan Chen