对图像进行霍夫变换检测直线。遍历图像，把极坐标下点转换到霍夫空间，同时累加器加1，最后统计累加器数组中的极大值点，便对应原图中的直线。(The image is transformed by Hof transform to detect the straight line. Traverse the image, transform the point in polar coordinates to Hof space, accumulate 1 at the same time, and finally count the maximum point in the accumulator array, which corresponds to the straight line in the original picture.)