中文说明：
边缘特征的提取就是求图像梯度的局部最大值和方向。实际计算中，以微分算子的形式表示，并采用快速卷积函数来实现。常用的算子有微分算子，拉普拉斯算子，Canny算子等。其中Canny边缘检测是一种较新的边缘检测算子，具有较好的边缘检测性能，得到越来越广泛的应用。Canny边缘检测法利用高斯函数的一阶微分，它能在噪声抑制和边缘检测之间取得较好的平衡
English Description：
Edge feature extraction is to find the local maximum and direction of image gradient. In practical calculation, it is expressed in the form of differential operator and realized by fast convolution function. Commonly used operators include differential operator, Laplace operator, Canny operator, etc. Canny edge detection is a new edge detection operator, which has better edge detection performance and has been more and more widely used. Canny edge detection method uses the first-order differential of Gaussian function, which can achieve a good balance between noise suppression and edge detection