傅立叶变换在熔池图像特征提取中的应用

Application of fourier transform in extraction of molten pool image character

熔池图像特征的提取对于分析焊接质量十分重要,而频域图像处理算法相对空域有很多优势,可以克服传统的空域图像处理算法对噪声敏感的不足,并有利于增强图像特征。为此,首先采用中值维纳滤波方法对焊接熔池图像进行组合滤波去噪,然后对去噪后的熔池图像运用基于傅立叶变换的巴特沃思滤波器进行高通滤波,以增强图像,并采用加强滤波算法对图像实现补偿,同时进行直方图均衡化,最后运用Canny算子边缘检测与数学形态学运算获得熔池边缘,提取出熔池特征信息。结果表明,运用傅立叶变换高频加强滤波进行熔池图像增强处理,并结合空域中较为成熟的图像处理算法,可以得到较好的熔池特征提取效果。

It is prerequisite to accurately extract the character of molten pool image for analyzing the welding quality. Frequency method of image processing has more advantages compared with the traditional spatial methods. The disadvantage of the later is sensitive to noises which can be overcome by the new method. The image character can be sharpened by image processing frequency methods. First, the Median-Winner filtering was used to eliminate the noises of the molten pool images. Then, the Butterworth high-pass filter based on the Fourier transform was used to strengthen the molten pool image. Also, the high frequency enhancement filtering arithmetic was applied to compensate the molten pool images. The molten pool images were processed by histogram equilibration. Finally, the Canny edge detection algorithm and erosion operation of mathematical morphology were applied to detect the molten pool edge. The experimental results showed that the improved high frequency enhancement method combined with the image processing spatial methods were effective to extract the molten pool image character.