一种基于自适应二值化阈值的焊缝边缘特征提取方法

A method for extracting edge features of welding seam based on an adaptive binary threshold

提出一种可靠提取焊缝边缘的图像处理方法。该方法通过对焊缝图像的梯度图像进行直方图均衡化,将梯度图像中反映边缘信息的像素的灰度级压缩到一个较小的范围内。然后,根据直方图均衡化后所得梯度图像的灰度级分布,确定图像的全局二值化阈值。以窗口半宽为步长在图像中滑动窗口,确定窗口内图像的局部二值化阈值。结合图像全局和局部二值化阈值,得到窗口内的自适应二值化阈值,对窗口内梯度图像进行二值化。此外,设计了一种迭代去噪的方法,以解决所得二值图像中存在大量噪声的问题。实际图像的测试结果表明了该方法的有效性。

This paper presents an image processing method which can extract the edge of welding seam reliably.Histogram equalization is performed on the gradient image of the original welding image to compress the gray distribution of pixels which represent the edge information of the image.Then the global binary threshold is determined.A small window is sliding on the histogram equalized gradient image with a step equal to half-width of the window to determine the local binary threshold in the window area.The adaptive binary threshold in the window area is obtained by combining the global and the local binary threshold.The image is binarized according to the adaptive binary threshold.Moreover,an iterative method is designed to remove noises in the binary image.The testing results of practical images demonstrate the validity of the method.