Regarding imshow (OpenCV with OpenGL support) (Bug #3352)

Added by Philipp Werner over 11 years ago. Updated over 9 years ago.

Status:	Open	Start date:	2013-10-30
Priority:	Normal	Due date:
Assignee:	-	% Done:	0%
Category:	highgui-gui
Target version:	-
Affected version:	2.4.6 (latest release)	Operating System:	Windows
Difficulty:		HW Platform:	x64
Pull request:

Description

The following code is giving flickering window without displaying any image.

Mat img = imread("image.jpg",CV_LOAD_IMAGE_ANYCOLOR);
namedWindow("window", WINDOW_OPENGL);
imshow("window",img);
waitKey(0);

and following code is working fine.

Mat img = imread("image.jpg",CV_LOAD_IMAGE_ANYCOLOR);
namedWindow("window", WINDOW_AUTOSIZE);
imshow("window",img);
waitKey(0);

Further, imshow() has the mentioned faulty behaviour if namedWindow() is not called explicitly and OpenCV has been compiled with OpenGL support.

I already found that adding a call to waitKey() before imshow() solves the problem, probably because it handles messages that need to be handled in between the creation of the window and the displaying of an image. So, this works:

Mat img = imread("image.jpg",CV_LOAD_IMAGE_ANYCOLOR);
namedWindow("window", WINDOW_OPENGL);
waitKey(0);
imshow("window",img);
waitKey(0);

However, this solution is neither documented nor consistent with OpenCV versions compiled without OpenGL support.

I am using Windows 7 64 bit, OpenCV 2.4.6.0 built with default settings + OpenGL-support. The same behaviour has been reported for OpenCV 2.4.3 with Windows 7 32 bit:
http://answers.opencv.org/question/7916/regarding-imshow-opencv-compiled-with-opengl/