Undistort image without cropping

[LeviMays]

I'm using cv2.undistort, but it crops the image. I'd like to have all the undistorted image, so that the undistorted size is bigger than the original one, like this:

See this post on stackoverflow, particularly the responses for Josep Bosch and andremkeller:
https://stackoverflow.com/questions/18742679/how-to-get-all-undistorted-image-with-opencv

I have tried to emulate the code andrewmkeller posted, using Python instead of C++, with some minor changes based on Josh Bosch's response. The result is the following:

  #!/usr/bin/env` python

  import cv2
  import numpy as np

  def loadUndistortedImage(fileName):
      # load image
      image = cv2.imread(fileName)
      #print(image)

      # set distortion coeff and intrinsic camera matrix (focal length, centerpoint offset, x-y skew)
      cameraMatrix = np.array([[894.96803896,0,470.38713516],[0,901.32629374,922.41232898], [0,0,1]])
      distCoeffs = np.array([[-0.340671222,0.110426603,-.000867987573,0.000189669273,-0.0160049526]])

      # setup enlargement and offset for new image
      y_shift = 60    #experiment with
      x_shift = 70    #experiment with    
      imageShape = image.shape  #image.size
      print(imageShape)
      imageSize = (int(imageShape[0])+2*y_shift, int(imageShape[1])+2*x_shift, 3)
      print(imageSize)
    
      # create a new camera matrix with the principal point offest according to the offset above
      newCameraMatrix, validPixROI = cv2.getOptimalNewCameraMatrix(cameraMatrix, distCoeffs, imageSize,
        1)
      #newCameraMatrix = cv2.getDefaultNewCameraMatrix(cameraMatrix, imageSize, True) # imageSize, True

      # create undistortion maps
      R = np.array([[1,0,0],[0,1,0],[0,0,1]])
      map1, map2 = cv2.initUndistortRectifyMap(cameraMatrix, distCoeffs, R, newCameraMatrix, imageSize,
        cv2.CV_16SC2)

      # remap
      outputImage = cv2.remap(image, map1, map2, INTER_LINEAR)
      #save output image as file with "FIX" appened to name - only works with .jpg files at the moment
      index = filename.find('.jpg')
      fixed_filename = filename[:index] +'_undistorted'+fileName[index:]
      cv2.imwrite(fixed_filename, outputImage)
      cv2.imshow('fix_img',outputImage)
      cv2.waitKey(0)
      return
    
  #Undistort the images, then save the restored images
  `loadUndistortedImage('./calib/WIN_20200626_11_29_16_Pro.jpg')

This seemed good to me, but then problems came up when trying to use cv2.getOptimalNewCameraMatrix or cv2.getDefaultNewCameraMatrix and cv2.initUndistortRectifyMap. I kept getting told that 'the argument takes exactly 2 arguments (3 given)' even though I am putting the parameters as specified in their documentation here: https://docs.opencv.org/2.4/modules/calib3d/doc/camera_calibration_and_3d_reconstruction.html https://docs.opencv.org/2.4/modules/imgproc/doc/geometric_transformations.html

I can remove the error from "...getDefault..." if I remove the optional params, but I'd rather not do that.

Stacktrace:

Traceback (most recent call last):
  File ".\main.py", line 46, in <module>
    loadUndistortedImage('./<image file name>.jpg')
  File ".\main.py", line 27, in loadUndistortedImage
    newCameraMatrix, validPixROI = cv2.getOptimalNewCameraMatrix(cameraMatrix, distCoeffs, imageSize, 1)
TypeError: function takes exactly 2 arguments (3 given)

[skvark]

Why you are asking this question here? This is the issue tracker of the opencv-python build toolchain, not a generic code related QA forum. There are specific places for this kind of questions:

• https://stackoverflow.com
• https://answers.opencv.org/questions/

I really hope this isn't some homework task, but I'll provide you an answer because it was very obvious with a quick glance of the code. In the future, do not open issues here unless the issue has something to do with the build scripts or generated binaries related to this repository.

First, I assume you are using the latest opencv-python version which is 4.3.0. Your link leads to OpenCV 2.4, which is like maybe 7 years old release. Here is the correct link to documentation: https://docs.opencv.org/4.3.0/d9/d0c/group__calib3d.html#ga7a6c4e032c97f03ba747966e6ad862b1

The issue is that you have 3 components in your image size: (x, y, z) instead of just (x, y) hence the error TypeError: function takes exactly 2 arguments (3 given).

You have also some other variable name related issues in the script you provided, but you'll have the figure those out by yourself.

[LeviMays]

@skvark I'm not your washed-up grade-school bully. I'm just new, so don't talk down to me and please excuse me.
Anyways, thank you for your help. And I'll keep in mind what sort of issues ought to be opened here and what sort don't belong.

[skvark]

Sorry for my response, I just get a lot of these random questions which take a lot of my time to go through and sort out. That's why there is the issue template which needs to be filled. Github issue trackers are reserved for bug reports and feature requests related to the code in the repositories.