In image processing, edges (or contours) refer not only to lines representing the boundaries of objects but also include line elements that depict image features, similar to the lines in a sketch. Of course, besides lines, colour and brightness are also important factors in images. However, many illustrations, charts, drawings, portraits, and comics are expressed using the method of depicting the object's edge lines. Although somewhat monotonous, we can still clearly comprehend what has been depicted there. Therefore, it seems somewhat incredible that simple edge lines can enable us to comprehend the object being expressed. For image processing, edge detection is also one of the important basic operations. The extracted edges can be used to identify specific objects, measure the area and perimeter of objects, find corresponding points between two images, and the processing of edge detection and extraction can further be used as a key pre-processing step for more complex image recognition and understanding.