camera_calibration - override enough data check

Hi everybody, I'd like to calibrate a stereo rig with the camera_calibration stereo node. I have a set of pre-recorded images that I publish using a simple ad-hoc player node and with some datasets it works pretty well. I followed [stereo tutorial](http://wiki.ros.org/camera_calibration/Tutorials/StereoCalibration) and *if* the number of images in my sequence is enough no problem arises. The problem is when I do not have *enough frames* and the calibrate button never lights. Do you know how I can override the *good enough* check? Thank you, Augusto