import numpy as np
import cv2
import os

def cv2_imread(filename, mode=-1):
    # 0:gray
    # 1:rgb
    # -1 any, read as the mode of source itself.
    # like cv2.imread
    cv_img = cv2.imdecode(np.fromfile(filename, dtype=np.uint8), mode)
    return cv_img

def cv2_imwrite(filename, img, suffix=None):
    # like cv2.imwrite
    if suffix is None:
        suffix = os.path.splitext(filename)[-1]
    if suffix == '':
        suffix = '.png'
    cv2.imencode(suffix, img)[1].tofile(filename)