本文選題：QR碼　切入點(diǎn)：小波變換　出處：《南京理工大學(xué)》2017年碩士論文

【摘要】：隨著信息化時(shí)代的來臨,計(jì)算機(jī)科學(xué)的進(jìn)步以及手機(jī)的智能化,二維條碼越來越多地被應(yīng)用在各行各業(yè)中。QR碼作為第一種直接對非英文字符進(jìn)行編碼的二維條碼,因其獨(dú)特的編碼特性和快速響應(yīng)的優(yōu)點(diǎn),目前已經(jīng)在我國的二維條碼市場中占據(jù)著主導(dǎo)地位。然而,在日常生活中和工業(yè)生產(chǎn)中,采集到的QR碼圖像往往存在光照不均衡、扭曲形變、背景復(fù)雜等問題,在這些情況下QR碼很難被正確地識(shí)讀出來。因此,對QR碼識(shí)別技術(shù)進(jìn)行深入地研究具有十分重要的意義。QR碼在識(shí)別的過程中涉及到的算法主要有圖像預(yù)處理算法、定位算法和校正算法。這些算法的目的是為了提取出清晰規(guī)整的QR碼符號(hào),便于對其譯碼。本文深入研究了QR碼識(shí)別的相關(guān)技術(shù),并實(shí)現(xiàn)了針對光照不均衡,扭曲形變,背景較為復(fù)雜的QR碼識(shí)別算法。首先,本文結(jié)合了 QR碼符號(hào)的特點(diǎn),實(shí)現(xiàn)了圖像預(yù)處理算法。圖像預(yù)處理可以分為灰度變換、光照均衡、濾波去噪和二值化這四個(gè)步驟。針對灰度變換,采用了符合人體視覺的YUV線性變換算法;針對光照不均衡,采用了簡單而有效的直方圖均衡化算法;針對噪聲,詳細(xì)研究了小波變換算法,并將其應(yīng)用在QR碼圖像的去噪中;針對二值化,重點(diǎn)分析了 Otsu算法,并對其進(jìn)行了改進(jìn)。實(shí)驗(yàn)結(jié)果表明,本文實(shí)現(xiàn)的圖像預(yù)處理算法能有效地去除圖像中的干擾信息,并且極大地增強(qiáng)了圖像的對比度。接著,本文在數(shù)學(xué)形態(tài)學(xué)以及邊緣檢測算法的基礎(chǔ)上,實(shí)現(xiàn)了QR碼定位算法,并對其進(jìn)行了改進(jìn)和優(yōu)化。實(shí)驗(yàn)結(jié)果表明,改進(jìn)優(yōu)化后的算法能有效地除去無用的背景信息,獲取完整的QR碼符號(hào),定位效果準(zhǔn)確。然后,本文在最小二乘法和反透視變換的基礎(chǔ)上,實(shí)現(xiàn)了QR碼校正算法,并且針對校正圖像的灰度值不連續(xù)的問題,采取了雙線性插值法對其進(jìn)行插值優(yōu)化。實(shí)驗(yàn)結(jié)果表明,該QR碼校正算法可有效地校正畸變的QR碼,復(fù)原其真實(shí)形狀。最后,研究了譯碼算法,并對QR碼進(jìn)行解讀,得到了其中包含的準(zhǔn)確信息。總體而言,本文所實(shí)現(xiàn)的QR碼識(shí)別算法,滿足了識(shí)別系統(tǒng)對實(shí)時(shí)性與準(zhǔn)確性的要求,具有一定的實(shí)際應(yīng)用價(jià)值。
[Abstract]:With the advent of the information age, the progress of computer science and the intelligence of mobile phone, two-dimensional bar code is more and more used in various industries. QR code is the first kind of two-dimensional bar code that directly encodes non-English characters.Because of its unique coding characteristics and the advantages of fast response, it has occupied a dominant position in the two-dimensional barcode market in China.However, in daily life and in industrial production, QR code images often have problems such as uneven illumination, distorted deformation, complex background and so on. In these cases, QR code is difficult to be correctly read out.Therefore, it is very important to study the recognition technology of QR code. The main algorithms involved in the recognition of QR code are image preprocessing algorithm, location algorithm and correction algorithm.The purpose of these algorithms is to extract clear and regular QR symbols and to decode them easily.In this paper, the related technology of QR code recognition is deeply studied, and an algorithm for QR code recognition is implemented, which is aimed at the uneven illumination, distorted deformation and complex background.Firstly, the image preprocessing algorithm is realized by combining the character of QR symbol.Image preprocessing can be divided into four steps: grayscale transformation, illumination equalization, filter denoising and binarization.Aiming at gray level transformation, YUV linear transform algorithm is adopted in accordance with human vision; aiming at illumination imbalance, simple and effective histogram equalization algorithm is adopted; wavelet transform algorithm is studied in detail for noise.It is applied to the denoising of QR code image, and the Otsu algorithm is analyzed and improved for the binarization.The experimental results show that the proposed image preprocessing algorithm can effectively remove the interference information from the image and greatly enhance the contrast of the image.Then, on the basis of mathematical morphology and edge detection algorithm, QR code location algorithm is implemented, and it is improved and optimized.The experimental results show that the improved algorithm can effectively remove the useless background information and obtain the complete QR symbol, and the localization effect is accurate.Then, based on the least square method and the inverse perspective transform, the QR code correction algorithm is implemented, and the bilinear interpolation method is adopted to optimize the QR code correction algorithm for the discontinuity of the gray value of the corrected image.Experimental results show that the QR code correction algorithm can effectively correct the distorted QR code and restore its real shape.Finally, the decoding algorithm is studied, and the QR code is interpreted to obtain the accurate information contained therein.In general, the QR code recognition algorithm realized in this paper meets the requirements of real-time and accuracy of the recognition system, and has certain practical application value.
【學(xué)位授予單位】：南京理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TP391.44

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本文編號(hào)：1707445