opencv > pil

import cv2  
from PIL import Image
img = cv2.imread("test.png")
image = Image.fromarray(cv2.cvtColor(img,cv2.COLOR_BGR2RGB))  

pil > opencv

import cv2  
from PIL import Image 
image = Image.open("test.png")  
img = cv2.cvtColor(numpy.asarray(image),cv2.COLOR_RGB2BGR)