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### imshow displays image too wide

I installed OpenCV 3 on my Mac (El Capitan, 10.11.6) via homebrew and tried to load and display an image by using exactly the code from this tutorial.

For some reason the output window looks like this:

So there is this gray area added which is as big as the original image.

Furthermore this leads to some more problems:

1.onMouse Callback reports wrong click positions: I attached this onMouse Callback to the window to log positions of my clicks:

static void onMouse( int event, int x, int y, int, void* ){
if( event != EVENT_LBUTTONDOWN ) return;
cout << "You clicked on (" << x << "," << y << ")" << endl;}


The results are:

• When I click in the middle of the 4 coloured fields (should be 50,50): (25,50)
• When I click in the bottom right corner of the blue field (should be 100,100): (50,100)
• When I click in the bottom right corner of the gray area: (100,100)

2.I tried to extend the onMouse callback to print the colour of the pixel that was clicked:

static void onMouse( int event, int x, int y, int, void* ){
if( event != EVENT_LBUTTONDOWN ) return;
cout << "You clicked on (" << x << "," << y << ")" << endl;
Vec3b bgrPixel = image.at<Vec3b>(x, y);
cout << "The color of this pixel is: " << bgrPixel << endl;}

• When i click into the black area i get: You clicked on (11,18). The color of this pixel is: [0, 0, 0] (CORRECT)

• When i click into the green area i get: You clicked on (37,23).The color of this pixel is: [0, 0, 0] (WRONG)

• When i click into the red area i get: You clicked on (10,72). The color of this pixel is: [1, 255, 0] (WRONG)

• When i click into the blue area i get: You clicked on (35,74). The color of this pixel is: [1, 255, 0] (WRONG)

My theory is that there is a problem with the datatype of the pixel BGR-values which are stored in the image Mat, but as I'm completely new to OpenCV I'm stuck at this point and don't know how to solve this problem.