imshow() producing weird results with OpenCV 3.2 in C++

Question

I am taking in RGB data from my Kinect and trying to put it into an OpenCV matrix. The data is held in "src":

Mat matrixImageRGBA(w, h, CV_8UC4);
memcpy(matrixImageRGBA.data, src, sizeof(byte) * w * h * 4);

However, when I use "imshow" to see the image, it is tiled four time horizontally. I am using the following command:

imshow("Window", matrixImageRGBA);
waitKey(500);

Does anyone have any idea of what the problem may be here? It's driving me nuts.

Thanks!

How are you getting the Kinect data? It sounds like it's not in the format you specified. — molbdnilo, May 08 '17 at 19:26
w and h are in the wrong order in the Mat constructor, if w is width and h is height. See http://stackoverflow.com/questions/25642532/opencv-pointx-y-represent-column-row-or-row-column/25644503#25644503 for possible reasons. — Micka, May 08 '17 at 21:18

score 3 · Accepted Answer · answered May 08 '17 at 19:50

You have w and h backwards. According to the docs the constructor takes the height as the first argument:

Mat (int rows, int cols, int type)

Also, I would recommend using this constructor:

Mat(int rows, int cols, int type, void *data, size_t step=AUTO_STEP)

instead of copying to the data field (since you are using no padding at the end of each row use the default AUTO_STEP for step).

1 Answers1