利用opencv来预处理图片：
1.高斯模糊
2.图片锐化

class ProcessImg(object):
    def __init__(self, img, sigma):
        self.img = img
        self.sigma = sigma

    def gaussian_img(self):
        """image gaussian blur"""
        gaussian_img = cv2.GaussianBlur(self.img, (3, 3), self.sigma)
        plt.imshow(gaussian_img.astype(np.int32)[:,:,::-1])
        plt.show()
        # cv2.imwrite(save_path + 'guassian_img.png', gaussian_img)
    def sharpen_img(self):
        """image sharpen"""
        kernel = np.array([[0,-1,0],[-1,5,-1],[0,-1,0]], np.float32)
        img_sharpen = cv2.filter2D(self.img, -1, kernel=kernel)
        plt.imshow(img_sharpen.astype(np.int32)[:, :, ::-1])
        plt.show()
        # cv2.imwrite(save_path  + 'sharp_img.png', img_sharpen)

img = cv2.imread('test.png')
plt.imshow(img.astype(np.int32)[:, :, ::-1])
plt.show()
A = ProcessImg(img, 0.5)
A.gaussian_img()
A.sharpen_img()