Michael Pfeuti

When starting a compiled wxWidgets application in Mac OS X you may have problems getting the focus of the application. You can solve this problem by creating a Mac OS X bundle application and start this instead of the binary:

http://wiki.wxwidgets.org/WxMac_Issues#Building_a_MacOSX_application_bundle

Make sure you configure Xcode (or whatever IDE you are using) to use the bundle or start the application manually.

Since, OpenCV’s documentation is more than lacking a few sentences I’ll post some important facts that can easily be missed.

To access the elements of a cv::Mat one can use the at<T>(int y, int x) method. Usually, the elements are stored as doubles (CV_64F). So to get for example elements (1,1) the call is

mat.at<double>(1,1);

but you’re not forbidden to call

mat.at<float>(1,1);

OpenCV won’t complain that you’re reading the wrong data type. OpenCV also doesn’t perform a type conversion. Hence, you’ll end up with the wrong data.

In summary, make sure you’re reading the correct data type. You might use the depth() method to figure out the internal type of the matrix

To tell the compiler to print warnings, add debugging symbols and profiling code add the following line to your CMakeLists.txt

set(CMAKE_CXX_FLAGS "-Wall -g -pg")

as usual -Wall specifies the warning level -g enables debugging and -pg profiling.