PiCode: A Multi-Scale Structure Similarity Metric (MS-SSIM) for Perceptual Quality Improvement

PiCode combines the attractive appearance of a picture and the decoding reliability of barcode. It offers a superior solution for mobile advertisement, media and marketing. Users can directly scan the PiCode for accessing information, while the advertiser would not have to stress over the valuable advertisement space occupied by the traditional 2D barcodes any more. Picode is typically used for embedding messages and image of the product logo such that people can conveniently use mobile devices to capture the Picode and acquire information through a QR code reader. In this proposed system, Picode with aesthetic elements has been formulated as an optimization problem that minimizes the visual perception distortion subject to acceptable decoding rate. However, the visual quality of the Picode generated by existing methods still leaves much to be desired. The poor visual quality is first synthesized based on the improvements of PiCode in three aspects: less obtrusive finder pattern, no fixed pattern in the interior of the barcode, and the use of adaptive modulation. The proposed PiCode as well as other beautified QR codes introduce distortions to the embedded image since data bits are carried by the modules via customized modulation schemes. To evaluate such distortions, the multi-scale structural similarity (MS -SSIM) metric is employed in our experiment to cater for different viewing conditions, such as different resolutions and physical sizes of the barcode.