Revision history [back]

waitKey() contains the whole message loop for the window.

when you do a imshow(), only a Mat header is copied, the actual blitting / drawing gets triggered later in the waitKey(). (that's why imshow() is so fast and waitKey() is so slow in your measurement above)

also, when your os is doing something heavy, and stalls your main thread for a moment, it will show up in this place.

calling it just 'waitKey()' might be a bit iof a misnomer ...

waitKey() contains the whole message loop for the window.

when you do a imshow(), only a Mat header is copied, the actual blitting / drawing gets triggered later in the waitKey(). (that's why imshow() is so fast and waitKey() is so slow in your measurement above)

also, when your os is doing something heavy, and stalls your main thread for a moment, it will show up in this place.

calling it just 'waitKey()' might be a bit iof a misnomer ...

int frameCounter=0;
while(1){
        frame = camera->GetLatestFrame();   
        if(frame){                      
            frame->Rasterize(cameraWidth, cameraHeight, imageCV.step, BITSPERPIXEL, imageCV.data);
        }
        if (++frameCounter % 10 ==0)  {
            imshow("V120", imageCV); 
            waitKey(1);                     
        }
        frame->Release();                   
    }

waitKey() contains the whole message loop for the window.

when When you do a imshow(), only a Mat header is copied, the actual blitting / drawing gets triggered later in the waitKey(). (that's why imshow() is so fast and waitKey() is so slow in your measurement above)

also, Also, when your os is doing something heavy, and stalls your main thread for a moment, it will show up in this place.

calling Calling it just 'waitKey()' might be a bit iof of a misnomer ...

still, Still, you don do not have to draw the image each time in the loop, and don't have toacall to call waitKey() each time:

int frameCounter=0;
while(1){
        frame = camera->GetLatestFrame();   
        if(frame){                      
            frame->Rasterize(cameraWidth, cameraHeight, imageCV.step, BITSPERPIXEL, imageCV.data);
        }
        if (++frameCounter % 10 ==0)  {
            imshow("V120", imageCV); 
            waitKey(1);                     
        }
        frame->Release();                   
    }