C++ OpenCV Rectification

#include <opencv2/opencv.hpp>

// Use the 3x3 M projection matrix from the intrinsic calibration
cv::Mat M = ...;

// Use D distortion from the intrinsic calibration (5 or 8 parameters in the standard OpenCV ordering)
cv::Mat D = ...;

// Use the 3x3 R rotation matrix from the extrinsic calibration
cv::Mat R = ...;

// Use the 3x4 P camera projection matrix from the extrinsic calibration
cv::Mat P = ...;

// Width of the output rectified image
int width = ...;

// Height of the output rectified image
int height = ...;

// Output lookup tables for the x and y output image dimensions
cv::Mat remap_x;
cv::Mat remap_y;

cv::initUndistortRectifyMap(M, D, R, P, cv::Size(width, height), CV_32FC1, remap_x, remap_y)

cv::Mat unrectified_image = cv::imread("unrectified_image.png);

cv::Mat rectified_image

// Interpolate using the remap lookup tables using bi-linear interpolation
cv::remap(unrectified_image, rectified_image, remap_x, remap_y, cv::INTER_LINEAR);

cv::imwrite("rectified.png", rectified_image);