读取文件为bytes类型：

def readfile2img_bytes():
    with open(img_path,'rb') as f:
         img_bytes = f.read()
   return img_bytes

读取bytes类型的图片转换为bgr：

 def read_img_bytes2_cv2img(img_bytes):
        arr1 = np.frombuffer(img_bytes,np.uint8)
        cv2_img = cv2.imdecode(arr1,cv2.IMREAD_COLOR)
        return cv2_img

读取bytes类型的图片转换为灰度图片：

def read_img_bytes2_cv2imggray(img_bytes):
        arr1 = np.frombuffer(img_bytes,np.uint8)
        cv2_imggray = cv2.imdecode(arr1,cv2.IMREAD_GRAYSCALE)
        return cv2_imggray

读取bgr类型的图片转换为灰度图片：

def cv_img2gray(cv_img):
        gray = cv2.cvtColor(cv_img,cv2.IMREAD_GRAYSCALE)
        return gray

读取中文路径的图片转换为bgr图片：

def read_img_for_chinese_path(file_path):
        cv_img = cv2.imdecode(np.fromfile(file_path, dtype=np.uint8), cv2.IMREAD_COLOR)
        return cv_img

保存中文路径的图片：

def save_img_for_chinese(cv_img,save_path):
        cv2.imencode('.jpg', cv_img)[1].tofile(save_path)