Use "distortPoints" to apply barrel distortion to an image

Hi,
My usecase is as follows: Given a rectilinear image, apply a barrel distortion to it.
I have my camera calibrated and have the K and D matrices. I use a mesh grid. Convert the coordinates to homogenous, multiply with K inv and then send them to cv2.distortPoints(). Now the output of this does not seem to be reasonable. How do I use this output get the distorted image?
Thanks

My usecase is as follows: Given a rectilinear image, apply a barrel distortion to it.

Probably you should use cv::remap().