How do I know what is the problem with "stereoParams" output from Stereo Calibration Tool ? The output of rectifyStereoImages are black images

I am running the calibration tool to get the parameters, with a mean error of less than a pixel. But when I use these parameters to "rectifyStereoImages" function. the rectified images are just generally black images. I am not sure why this happening, It does not happen when I use stereoParams from an example. What is wrong with my "stereoParams"?

if true
  frameLeft = imread('cal_L_2.png');
  frameRight = imread('cal_R_2.png');
  imshow(frameLeft);
  [frameLeftRect, frameRightRect] = rectifyStereoImages(frameLeft, frameRight, stereoParams);
  figure;
  imshow(stereoAnaglyph(frameLeftRect, frameRightRect));
  title('Rectified Video Frames');
end

Answer 1

[Don Zheng]

Make sure that 'frameLeftRect' and 'frameRightRect' are expected rectified images and 'imshow'able separately. Also, make sure there are enough distinct key points other than the calibration grids for pattern matching.

Also worth trying other example images from the documentation to identify at which step things go wrong.

[Goku]

The example parameters works well. And when I update the function "rectifyStereoImages" to

rectifyStereoImages(frameLeft, frameRight, stereoParams,'Output','full');

and it now gives me two very separate images, I don't understand why this behavior:

[Don Zheng]

Were you getting cropped images for 'frameLeftRect' and 'frameRightRect' without 'full' 'Output'?

[Goku]

Yes, they are cropped without 'full', would you happen to know the reason for that?