Hi.
First thanks for your answer. I tried to run the project on the Linux machine(Raspberry with raspbian), and it opens a QMessageBox propperly and then opens two OpenCV windows but all in grey, neither source image not contour image are shown in the windows. It happens the same running it on the linux machine or on Windows with XMing.
So I tried to create a simple OpenGL project, and it runs well in both XMing under windows and in the local linux machine. So, it seems that something is missing in the project? Any library or something? I have to add OpenGL libraries somewhat in the project? Or are included with the Qt or OpenCV libraries?