cv_bridge and IplImage -> Mat when going from OpenCV 2.1 to OpenCV 2.3?

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Many thanks @diaz! Do you happen to know what type of Mat is returned by GetMat? For example, if I use 'frame = cv.GetMat(self.bridge.imgmsg_to_cv(ros_image, "bgr8"))', what Mat type is frame? e.g. 8UC3, 32FC3? etc. I ask because I'm still having size and/or type compatibility problems when trying to copy or perform other operations with the 'frame' matrix and other image matrices in my code.

I'm not sure what the correspondence is between IplImage encodings and the regular Mat encodings, but it should be semantically equivalent. bgr8 would likely give you 8UC3 or something similar. When creating new Mats of the same type, you can be encoding-agnostic by using mat.type and mat.channels.

Thanks again @diaz. Yes, it looks like its type 8UC3 or 16 in integer format.

Could you post code that requires converting to a numpy array? Most OpenCV functions work on array-like objects, and Mats certainly are. I just tried cv.CvtColor using a Mat as the source and destination, and it works fine.

OK, I jumped the gun. It looks like it is only the functions in cv2 that require a numpy array. In the lk_track.py demo the convert function used is cv2.cvtColor and this requires a numpy array whereas the old cv.CvtColor does not. Similarly, the new cv2.goodFeaturesToTrack requires numpy arrays.