Fig. 1. Symbolic characteristics of QR codes. (a) Structure of QR codes; (b) detection patterns

Fig. 2. Results comparison of QR codes binarization. (a) Original images of QR codes; (b) Otsu algorithm; (c) the proposed algorithm

Fig. 3. Search the central point of detection pattern. (a) Line scan; (b) column scan; (c) adjust to the center position; (d) judge the relationship between S1 and S2

Fig. 4. Position relationship of QR codes in the image

Fig. 5. Search of QR codes vertices. (a) Position analysis of detection pattern points; (b) contour tracing start point; (c) vertices of detection patterns; (d) the fourth vertex

Fig. 6. Inverse perspective transformation

Fig. 7. Correction results in different environments. (a) Normal illumination; (b) low light environment; (c) complex background environment

Fig. 8. Correction results of fuzzy image. (a) Light fuzzy; (b)(c) fuzzy

Fig. 9. Analysis of different algorithms. (a) Ref. [5] algorithm; (b) Ref. [13] algorithm; (c) Ref. [8] algorithm