I'm having trouble with using imgMsgToCv() function. I'm using it in a subscriber node to convert images acquired from a camera to opencv IplImage:

void imageCallback(const sensor_msgs::ImageConstPtr& msg)

{

sensor_msgs::CvBridge bridge;

IplImage* imgB = bridge.imgMsgToCv( msg, "mono8");

.

.

in this way things work but I need imgB to be a global variable and when I try to write things like this:

IplImage* imgB;

void imageCallback(const sensor_msgs::ImageConstPtr& msg)

{

sensor_msgs::CvBridge bridge;

imgB = bridge.imgMsgToCv( msg, "mono8");

.

I get this error:

.

/home/dede/electricworkspace/sandbox/labrobrosquadrotor/labrobproject/src/viewer.cpp:20:49: error: no match for ‘operator=’ in ‘imgB = bridge.sensormsgs::CvBridge::imgMsgToCv(boost::sharedptr > >((* & msg)), std::basic_string(((const char)"mono8"), ((const std::allocator*)(& std::allocator()))))’

/home/dede/electricworkspace/sandbox/labrobrosquadrotor/labrobproject/src/viewer.cpp:20:49: note: candidate is: /usr/include/opencv-2.3.1/opencv2/core/typesc.h:447:16: note: _IplImage& _IplImage::operator=(const _IplImage&) /usr/include/opencv-2.3.1/opencv2/core/typesc.h:447:16: note: no known conversion for argument 1 from ‘IplImage* {aka _IplImage*}’ to ‘const _IplImage&’

/home/dede/electricworkspace/sandbox/labrobrosquadrotor/labrobproject/src/viewer.cpp:25:25: error: ‘sensormsgs::CvBridge::cvbridge’ has not been declared

but I can't understand where is the problem, any hints on it?