针对直接零件标记(DPM, Direct Part Marking)二维条码的定位技术展开研究。由于环境光照、金属材质等因素,采集到的条码图像会存在光照不均、对比度低和高光等问题,对DPM二维条码定位带来很大的影响。采用了同态滤波的方法来增强图像,用梯度投影法对二维条码区域进行初定位。针对背景灰度级与目标灰度级相近导致传统阈值化存在误分割的问题,采用了一种OSTU与邻域阈值相结合的自适应二值化算法。利用形态学拟合Data Matrix二维条码的L型定位边,最后采用凸包算法实现对二维条码精定位。实验表明,该方法能有效解决图像采集中出现的光照不均、对比度低等问题,快速定位出条码区域。%The locating method of DPM 2D barcode image is studies in this paper. Because of the issue of reflective light of metal surface and the uneven surface, the DPM 2D barcode image collected will be of uneven illumination, low contrast, high light and other issues. These problems will impact on locating of DPM barcode greatly. In this paper, the homomorphic filtering method is used to enhance the image and the gradient projection method is used to locate the barcode region in preliminary. Because of the similar gray level between background and barcode which will result in segmentation error in the traditional thresholding method, an adaptive binarization method composed of Otsu method and neighborhood threshold method is used in this paper. Then the mathematical morphology method is used to fitting the “L” shape of Data Matrix barcode. Finally the convex hull algorithm is used to locate barcode region precisely. Experiment result shows that this method can solve uneven illumination and low contrast effectively and locate the barcode region quickly.
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