QR Code Recognition Algorithm And Its Application In Iphone

Recently, QR Code has become more and more popular in China. In themobile software market, a large number of softwares combined with QR Codeappear. It has become a powerful weapon to promote the network and market. Wecan easily get information, such as media coverage and retail discounts, byscanning QR code. These make it enter the life of ordinary people from enterprises.The recognition algorithm of QR code and its application including imageacquisition, preprocessing and recognition were investigated in this paper. Themain contents in the algorithm are image acquisition, preprocessing and recognition.The algorithm was also implemented in iPhone.First, the development of the two-dimensional code and it’s applications inmarket is described. The application of mobile two-dimensional code domestic andabroad is introduced too.Second, the basic structure and the coding theory of the QR code, whichwere the foundation for QR code recognition algorithm.Based on the aforementioned contents，the process and algorithm of QR coderecognition were described in detail, including color to gray transformation, binaryconversion, image correction, sampling and data reading. Then a new median filteralgorithm based on traditional median filtering algorithm. The algorithm is basedon the narrowing of grayscale within a single window and multiple noise filtering.This method can filter noise and protect the details of the image at the same time.The effect is good when salt and pepper noise was relatively large. When thedensity of salt and pepper noise reached50%, the peak signal to noise ratio ofmedian filter and multistage median filter were22.7525and9.7534, the newmethod is27.5051. The mean square error of median filter and multistage medianfilter were0.012and0.2391, the new method is only0.004. Finally, the QR code recognition algorithm is implemented on iPhoneplatform using Xcode as programming platform and Objective-C as programminglanguage.