主要是采用Canny算法进行边缘检测，有一个个跟踪条，涉及到callback函数，对灰度图像进行边缘检测，将彩色图像转换为灰度图像-Using Canny algorithm for edge detection, a track bar relates to the callback function, for edge detection of gray image, the color image is converted to grayscale images