Toward Robust Color Recovery for High-Capacity Color Qr Codes Supplementary Material

TOWARD ROBUST COLOR RECOVERY FOR HIGH-CAPACITY COLOR QR CODES SUPPLEMENTARY MATERIAL Zhibo Yang, Zhiyi Cheng, Chen Change Loy, Wing Cheong Lau, Chak Man Li, Guanchen Li The Chinese University of Hong Kong 1. CUHK-CQRC: A LARGE-SCALE COLOR QR CODE DATASET We propose a challenging color QR code dataset, CUHK- CQRC1, in this paper. CUHK-CQRC consists of 1,506 photos and 3,884 camera previews (video frames) of high-density 3-layer color QR codes captured by different phone models under different lighting conditions. Fig. 1 presents some samples of CUHK-CQRC. Different from [1], we also in- clude previews in our dataset because of the two reasons. Firstly, photos are different from previews. When users take a photo using the on-board camera of a mobile phone, many embedded systems implicitly process (e.g., lightweight de- blurring and color correction) the output image in order to make it more attractive in appearance, while preview will not Fig. 1. Samples from CUHK-CQRC captured under different go through this process. Secondly, compared with capturing lighting conditions. photos, it is much faster and more cost-effective for a cell- phone camera to generate previews, and hence most mobile applications use camera previews as the input of the decoder. Table 1. Types of Smartphones Used in Collecting Database. We implement the color QR code generator based on ID Modle MegapixelsImage Stabi- Autofocus an open-source barcode processing library, ZXing, and Name (MP) lization we also deploy the HiQ generator on-line at https:// 1 iphone 6 plus 8.0 X(optical) X authpaper.net/. For fair comparison between HiQ-C 2 iphone 6 8.0 X(digital) X and PCCC in which the color QR code is inherently 3-layer, 3 Nexus 4 8.0 X so we generate 5 high-capacity 3-layer color QR codes with 4 Meizu MX2 8.0 X different data capacities (excluding redundancies from error 5 Oneplus 1 13.0 X correction mechanism) which are 2787 bytes, 3819 bytes, 6 Galaxy 5.0 X 5196 bytes, 6909 bytes and 8859 bytes (maximum for a Nexus 3 3-layer color QR code). In order to test the limit of each 7 Sony Xperia 8.0 X approach, all color QR codes are embedded with low level M2 of error correction in each layer. By using a common color 8 Nexus 5 8.0 X(optical) X printer (Ricoh Aﬁcio MP C5501A), we print each generated color QR code on ordinary white paper substrate in different printout sizes, 30 mm, 40 mm, 50 mm and 60 mm (for images using eight types of popular smartphones see Table 1 simplicity, we use the length of one side of the square to for details. represent the printout size), and two different printout resolu- tions, 600dpi and 1200dpi. To simulate the normal scanning 2. ADDITIONAL EXPERIMENTAL RESULTS scenario, the samples are captured by different users under several typical lighting conditions: indoor, outdoor (under To provide better understanding of our method, we present different types of weather and time duration of a day), ﬂu- detailed experimental results of the usability study (Sec. 5 of orescent, incandescent, and shadowed (both uniform and the main paper), see Fig. 2. For each printed HiQ code, we nonuniform cases are considered). Moreover, we capture the collect the scanning time (in seconds) of 30 successful trials 1https://authpaper.net/colorDatabase.html (i.e., trials where the HiQ code is successfully decoded) using 35 35 35 LLL LLL 30 30 30 LLL LLM LLM LLM 25 25 25 LLQ LLQ LLQ 20 20 MMM MMM 20 MMM 15 15 15 10 10 10 Scanning Time (s) Scanning Time (s) 5 5 Scanning Time (s) 5 0 0 0 22 26 30 34 38 42 46 26 30 34 38 42 46 50 34 38 42 46 50 Physical Printout Size (mm) Physical Printout Size (mm) Physical Printout Size (mm) (a) 2000-byte color QR code. (b) 2900-byte color QR code. (c) 4500-byte color QR code. 35 35 35 LLL LLL 30 30 30 LLL LLM LLM 25 25 LLQ 25 20 MMM 20 20 15 15 15 10 10 10 Scanning Time (s) Scanning Time (s) 5 5 Scanning Time (s) 5 0 0 0 42 46 50 54 58 62 50 54 58 62 66 70 54 58 62 66 70 Physical Printout Size (mm) Physical Printout Size (mm) Physical Printout Size (mm) (d) 6100-byte color QR code. (e) 7700-byte color QR code. (f) 8900-byte color QR code. Fig. 2. Scanning performance of HiQ across various content sizes, printout sizes and error correction levels. iPhone 6 Plus. We use the 90th percentile, 10th percentile and median to represent the upper bound, lower bound of the scanning time and the overall performance. 3. REFERENCES [1] Henryk Blasinski, Orhan Bulan, and Gaurav Sharma, “Per-colorant-channel color barcodes for mobile applications: An interference cancellation framework,” Im- age Processing, IEEE Transactions on, vol. 22, no. 4, pp. 1498–1511, 2013..

Load more