Stereo points projection

I have a calibrated stereo setup (let’s name them L and R) with OpenCV. I used over 120 pairs of checkerboard images to perform the calibration. With the code provided by OpenCV (with some small modifications), I can compute all matrices, including (K1, K2, R, T, P1, P2, D1, D2, R1Ext, T1Ext, R2Ext, T2Ext, E, F, Q).

How can I project points from L to R using these matrices?