I get images from a camera where it is not possible to take a chessboard picture and calculate the correction matrix using OpenCV. Up to now I corrected the images using imagemagick convert with the option '-distort Barrel "0.0 0.0 -0.035 1.1"' where I got the parameters with trial and error.
Now I want to do this inside OpenCV but all I find in the web is the automatic correction using the chessboard image. Is there any chance to apply some simple manual trial and error lens distortion correction as I did with imagemagick?
Ok, I think I got it. In the matrices cam1, cam2 the image centers were missing (see documentation). I added it and changed the focal length to avoid a too strong change of image size. Here is the code:
import numpy as np
import cv2
src = cv2.imread("distortedImage.jpg")
width = src.shape[1]
height = src.shape[0]
distCoeff = np.zeros((4,1),np.float64)
# TODO: add your coefficients here!
k1 = -1.0e-5; # negative to remove barrel distortion
k2 = 0.0;
p1 = 0.0;
p2 = 0.0;
distCoeff[0,0] = k1;
distCoeff[1,0] = k2;
distCoeff[2,0] = p1;
distCoeff[3,0] = p2;
# assume unit matrix for camera
cam = np.eye(3,dtype=np.float32)
cam[0,2] = width/2.0 # define center x
cam[1,2] = height/2.0 # define center y
cam[0,0] = 10. # define focal length x
cam[1,1] = 10. # define focal length y
# here the undistortion will be computed
dst = cv2.undistort(src,cam,distCoeff)
cv2.imshow('dst',dst)
cv2.waitKey(0)
cv2.destroyAllWindows()
Thank you very much for your assistence.