Strange shape on undistorted iamge with notmal method

[LulaSan]

Thank you for your work.
I have aproble with my calibration.
(If it is correct that the size is in mm, then size is 100 otherwise it is 10 cm.)
Why it does look like this?
python intrinsicCalib.py -input image -path ./normal_chessboard/ -image cap_cameras_a_0_compressed -bw 10 -bh 7 -type normal -size 100 -fw 1440 -fh 960