Friday, 21 June 2013

OpenCV configuration and demo programs

So I configured OpenCV as below.

1.  sudo nano /etc/ to add the following line to the empty file.


2.  sudo nano /etc/bash.bashrc to add the following 2 lines to the end of the file.

    export PKG_CONFIG_PATH

Then I tried to run the programs convexhull and kmeans.  But both warning messages of not being able to open display.

3. pi@raspberrypi ~/fongvision $ cd OpenCV-2.3.1/build/bin

pi@raspberrypi ~/fongvision/OpenCV-2.3.1/build/bin $ sudo ./convexhull

This sample program demonstrates the use of the convexHull() function


(hull:2647): Gtk-WARNING **: cannot open display:

4. pi@raspberrypi ~/fongvision/OpenCV-2.3.1/build/bin $ sudo ./kmeans

(clusters:2649): Gtk-WARNING **: cannot open display:


Raspberry Pi + OpenCV POSTED BY MICHAEL ON JUN 14, 2012


*** Configure ***

Finally, we need to make a few configurations for OpenCV. First, open the opencv.conf file with the following code:

sudo nano /etc/

Add the following line at the end of the file (it may be an empty file, that is ok) and then save it:


Then edit the system-wide bashrc file:

sudo nano /etc/bash.bashrc

Add the following new lines to the end of the file:



*** Comments ***

Pete FEBRUARY 8, 2013

There is a small mistake in the step where you change the system-wide bashrc:
“PKG_CONFIG_PATH=$PKG_CONFIG_PATH:/usr/local/lib/pkgconfig export PKG_CONFIG_PATH”

How it should be:


“export” needs to be on the second line otherwise you get a ton of console spam and an error from that bashrc…


mrshu MARCH 1, 2013

Also, you need to run `sudo ldconfig` after you add anything to /etc/

*** C Demos ***

Now that everything is installed and configured, on to the demos!  The C demos are here:

cd ~/opencv/OpenCV-2.3.1/build/bin

C demos in build/bin demos worth checking out (that don’t require a webcam):




*** Python demos ***

The python demos are located in samples/python:

cd ~/opencv/OpenCV-2.3.1/build/bin

These demos also don’t require a webcam:

python ./

python ./

python ./


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