That's Not Helping, Python.

[ERROR] [WallTime: 1384556730.822164] bad callback: >
Traceback (most recent call last):
File "/opt/ros/groovy/lib/python2.7/dist-packages/rospy/topics.py", line 681, in _invoke_callback
cb(msg)
File "./board_finder.py", line 81, in callback
self.finder.getBoard(data)
File "./board_finder.py", line 68, in getBoard
newImg = cv2.warpPerspective(cvImg, perMat)
TypeError: Required argument 'dsize' (pos 3) not found

[ERROR] [WallTime: 1384556763.964408] bad callback: >
Traceback (most recent call last):
File "/opt/ros/groovy/lib/python2.7/dist-packages/rospy/topics.py", line 681, in _invoke_callback
cb(msg)
File "./board_finder.py", line 81, in callback
self.finder.getBoard(data)
File "./board_finder.py", line 68, in getBoard
newImg = cv2.warpPerspective(cvImg, perMat, newImg.shape)
TypeError: function takes exactly 2 arguments (3 given)

Well which is it? Exactly two arguments, or the third positional argument is required?

The real problem is that the shape of newImg is a 3-tuple, and warpPerspective expects a 2-tuple. This StackExchange post hipped me to the bug.