findChessboardCornersSB Fails

Hello! I’m trying to perform a 2d calibration using the findChessboardCornersSB function and it fails to find the chessboard on what I think should be a pretty straightforward image so I’m assuming I’m doing something kind of dumb.

The image in question:

The code:

import cv2

 checkerboard_size = (10, 15)

img = cv2.imread("Webcam-20230919-13:43:55-294.png")
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
ret, corners = cv2.findChessboardCornersSB(gray, checkerboard_size, cv2.CALIB_CB_EXHAUSTIVE)
cv2.drawChessboardCorners(img, checkerboard_size, corners, ret)

I’ve tried various combinations of cv2.CALIB_CB_EXHAUSTIVE, cv2. CALIB_CB_NORMALIZE_IMAGE, and cv2. CALIB_CB_ACCURACY with no impact. I’ve also tried preprocessing with binary thresholding but that doesn’t seem to make a difference either.

Any help would be appreciated!