Difference between revisions of "OpenCV"

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= OpenCV 2.3 =
 +
 +
The buildroot openCV package is not available yet in the buildroot version used by ARMadeus, however I will explain a little workaround to cross-compile this graphical library and use it on your ARMadeus plateform. I was inspired by the Opencv 2.1 section downwards.
 +
 +
This section has been written using an APF51 with the git-trunk ARMadeus version.
 +
 +
== Buildroot configuration ==
 +
 +
*Install lib4vl
 +
In your armadeus directory:
 +
<pre class="host">
 +
$ make menuconfig
 +
</pre>
 +
 +
<pre class="host">
 +
Package Selection for the target  --->
 +
  Hardware handling  --->
 +
    [*] libv4l
 +
      [*]  v4l2-ctl
 +
</pre>
 +
 +
*Take a look in...
 +
 +
<pre class="host">
 +
Package Selection for the target  --->
 +
  Libraries  --->
 +
    Graphics  --->
 +
</pre>
 +
 +
... if the interesting format (jpg, png etc ...) for your application is checked.
 +
 +
== Compiling and installing OpenCV-2.3.1 ==
 +
 +
*Prepare the directories
 +
<pre class="host">
 +
$ mkdir OpenCV-2.3.1
 +
$ cd OpenCV-2.3.1
 +
$ mkdir build
 +
$ mkdir src
 +
</pre>
 +
 +
*Get the source
 +
 +
<pre class="host">
 +
$ cd src
 +
$ wget http://sourceforge.net/projects/opencvlibrary/files/opencv-unix/2.3.1/OpenCV-2.3.1a.tar.bz2
 +
$ tar xvjf OpenCV-2.3.1a.tar.bz2
 +
$ cd ../
 +
</pre>
 +
 +
*Patch the source
 +
This (dirty?) patch fix a compatibility problem with the long double type on ARM plateforme (fabsl not available).
 +
 +
[[#OpenCV-2.3.1.patch| OpenCV-2.3.1.patch]]
 +
 +
<pre class="host">
 +
$ patch -p0 < OpenCV-2.3.1.patch
 +
</pre>
 +
 +
*Build Makefile from CMake
 +
 +
<pre class="host">
 +
$ cd build
 +
$ cmake -DCMAKE_BUILD_TYPE=RELEASE -DCMAKE_TOOLCHAIN_FILE:PATH=your_armadeus_directory/buildroot/output/toolchainfile.cmake -DCMAKE_INSTALL_PREFIX=your_armadeus_directory/buildroot/output/staging/usr/ -DCMAKE_BUILD_TYPE=RELEASE ../src/OpenCV-2.3.1/
 +
</pre>
 +
 +
Check if no error and the install path.
 +
You can configure your OpenCV compilation with...
 +
 +
<pre class="host">
 +
$ cmake-gui
 +
</pre>
 +
 +
*Build OpenCV-2.3.1
 +
 +
<pre class="host">
 +
$ make && make install
 +
</pre>
 +
 +
*Copy the libraries into your rootfs filesystem.
 +
In your armadeus directory:
 +
<pre class="host">
 +
$ cp buildroot/output/staging/usr/lib/libopencv_* buildroot/output/target/usr/lib/
 +
</pre>
 +
 +
== Test & example ==
 +
 +
This test was made with a Logitech QuickCam Communicate STX.
 +
 +
=== Configure your Linux Kernel ===
 +
 +
In your armadeus directory:
 +
 +
<pre class="host">
 +
$ make linux-menuconfig
 +
</pre>
 +
 +
Check if the V4L driver is correctly checked:
 +
 +
<pre class="config">
 +
Device Drivers  --->
 +
  <M> Multimedia support  --->
 +
    <M>  Video For Linux
 +
</pre>
 +
 +
And configure your driver, in our case for the Logitech QuickCam Communicate STX:
 +
 +
<pre class="config">
 +
Device Drivers  --->
 +
  <M> Multimedia support  --->
 +
    [*]  Video capture adapters  --->
 +
      [*]  V4L USB devices  --->
 +
        <M>  GSPCA based webcams  --->
 +
          <M>  ZC3XX USB Camera Driver
 +
</pre>
 +
 +
Reflash kernel and rootfs.
 +
 +
== Build your application ==
 +
 +
In your armadeus directory
 +
<pre class="host">
 +
$ cd buildroot/output/build
 +
$ mkdir opencv_example
 +
$ cd opencv_example
 +
</pre>
 +
 +
In this directory, copy these files:
 +
 +
[[#Makefile| Makefile]]
 +
 +
[[#opencv_example.c| opencv_example]]
 +
 +
<pre class="host">
 +
$ make
 +
</pre>
 +
 +
== Run the application test ==
 +
 +
On your APF board
 +
 +
<pre class="apf">
 +
# modprobe videodev
 +
# modprobe gspca_zc3xx
 +
</pre>
 +
 +
Where gspca_zc3xx corresponding to my logitech webcam.
 +
 +
Then run the opencv_example application et check the picture test.jpg.
 +
 +
= OpenCV 2.1 =
 
{{Under_Construction}}
 
{{Under_Construction}}
 
== Forewords ==
 
== Forewords ==
−
This page explains how to (cross-)compile [http://opencv.willowgarage.com/wiki| OpenCV 2.1.0] for your APF-board.
+
This section explains how to (cross-)compile [http://opencv.willowgarage.com/wiki OpenCV] 2.1.0 or later for your APF-board.
  
 
== Pre-requisite ==
 
== Pre-requisite ==
−
You need to have [[CMake]] installed on your system.
+
The CMake infrastructure has been integrated in Buildroot since the [http://git.buildroot.net/buildroot/plain/CHANGES?id=2011.02 BR release 2011.02].
 +
 
 +
The CMake infrastructure is available in armadeus SDK since the
 +
[http://armadeus.git.sourceforge.net/git/gitweb.cgi?p=armadeus/armadeus;a=blob;f=ChangeLog;hb=cbc69e2606aeb8ad56701b3191e9632dc8358653 armadeus-4.1 release] (since it is based on BR release 2011.05).
 +
 
 +
{{Note|Using elder armadeus SDK requires having [[CMake]] 2.6 or later installed on the host system.}}
  
 
== Build OpenCV ==
 
== Build OpenCV ==
−
# Edit your <!--[[Cmake#The_toolchain_file | ]]-->toolchain.cmake file
+
 
 +
{{Note|The tutorial hereafter (patch and OpenCV configuration) is for the OpenCV 2.1.0 release.
 +
 
 +
This may changes in newer OpenCV releases. Updates are welcome ;-)
 +
}}
 +
 
 +
# Setup the CMake toolchain file:
 +
## '''Using armadeus-4.1 SDK or later (or git view):''' this file is generated by buildroot and is located in ''armadeus-4.1/buildroot/output/toolchainfile.cmake''.
 +
## '''Using armadeus-4.0 SDK or former:''' the [[CMake#The_toolchain_file| toolchainfile.cmake]] must be manually edited.
 
# Create source and build directories <source lang="bash">
 
# Create source and build directories <source lang="bash">
 
mkdir -pv opencv-on-armadeus/{src,build}
 
mkdir -pv opencv-on-armadeus/{src,build}
 
</source>
 
</source>
−
# Grab the source archive <source lang="bash">
+
# Grab the OpenCV source archive.<source lang="bash">
−
cd opencv-on-armadeus/src && wget http://sourceforge.net/projects/opencvlibrary/files/opencv-unix/2.1/OpenCV-2.1.0.tar.bz2/dowload && tar xvvjf OpenCV-2.1.0.tar.bz2
+
cd opencv-on-armadeus/src && wget http://sourceforge.net/projects/opencvlibrary/files/opencv-unix/2.1/OpenCV-2.1.0.tar.bz2 && tar xvvjf OpenCV-2.1.0.tar.bz2
 +
</source>
 +
# Here, you'll have to apply [[#OpenCV-2.1.0.patch| this patch]] to avoid compilation failed: <source lang="bash">
 +
patch -p0 < OpenCV-2.1.0.patch
 
</source>
 
</source>
 
# Run CMake (generate Makefiles)
 
# Run CMake (generate Makefiles)
−
## <source lang="bash">
+
## <source lang="bash">
−
cd ../build && cmake -DCMAKE_TOOLCHAIN_FILE:PATH=/path/to/toolchain.cmake ../src/OpenCV-2.1.0
+
cd ~/opencv-on-armadeus/build && cmake -DCMAKE_TOOLCHAIN_FILE:PATH=/path/to/toolchainfile.cmake ../src/OpenCV-2.1.0
 
</source>
 
</source>
 
##It will certainly complain about unfound libraries and some other things, so adjust these things running:<source lang="bash">
 
##It will certainly complain about unfound libraries and some other things, so adjust these things running:<source lang="bash">
Line 35: Line 202:
  
  
−
== Available features ==
+
=== Available features (for armadeus-4.0 release or former) ===
−
CMake looks for all required tool in the path specified in <!--[[Cmake#The_toolchain_file|toolchain.cmake file]]--> toolchain.cmake file; therefore, some options, targets, libraries, ... are not available:
+
CMake looks for all required tool in the path specified in [[CMake#The_toolchain_file| toolchainfile.cmake]]; therefore, some options, targets, libraries, ... are not available:
  
 
* Build:
 
* Build:
Line 54: Line 221:
  
 
{{Note|You may need to enable some packages in your Armadeus configuration to get some libraries (libjpeg, libpng and libtiff) found by CMake.}}
 
{{Note|You may need to enable some packages in your Armadeus configuration to get some libraries (libjpeg, libpng and libtiff) found by CMake.}}
 +
 +
== Run OpenCV applications on your APF-board ==
 +
# In the ''build'' directory, you should find a ''bin'' and a ''lib'' sub-directories. Copy them (at least the ''lib'' directory) on your target.
 +
# <source lang="bash">
 +
export LD_LIBRARY_PATH=/path/to/the/OpenCVlibdir
 +
</source>
 +
# Run your application. You can try ''cvtest'' (some tests may fail because of missing resources),  it will take a while... a long while ;)
 +
 +
== See also ==
 +
* [http://opencv.willowgarage.com/wiki/InstallGuide OpenCV install guide]
 +
 +
= Appendices =
 +
== OpenCV-2.3.1.patch ==
 +
<source lang="diff">
 +
Index: src/OpenCV-2.3.1/modules/flann/include/opencv2/flann/dist.h
 +
===================================================================
 +
--- src/OpenCV-2.3.1/modules/flann/include/opencv2/flann/dist.h 2011-09-12 20:42:27.000000000 +0200
 +
+++ src/OpenCV-2.3.1/modules/flann/include/opencv2/flann/dist.h 2012-02-05 15:10:28.715982724 +0100
 +
@@ -60,7 +60,7 @@
 +
inline double abs<double>(double x) { return fabs(x); }
 +
 +
template<>
 +
-inline long double abs<long double>(long double x) { return fabsl(x); }
 +
+inline long double abs<long double>(long double x) { return fabs(x); }
 +
 +
 +
template<typename T>
 +
</source>
 +
== OpenCV-2.1.0.patch ==
 +
<source lang="diff">
 +
--- OpenCV-2.1.0/3rdparty/flann/constants.h.origin 2010-06-08 01:14:22.171416516 +0200
 +
+++ OpenCV-2.1.0/3rdparty/flann/constants.h 2010-06-08 01:15:06.912417891 +0200
 +
@@ -41,7 +41,7 @@ enum flann_algorithm_t {
 +
KMEANS = 2,
 +
COMPOSITE = 3,
 +
SAVED = 254,
 +
- AUTOTUNED = 255,
 +
+ AUTOTUNED = 255
 +
};
 +
 +
enum flann_centers_init_t {
 +
--- OpenCV-2.1.0/3rdparty/flann/flann.h.origin 2010-06-08 01:14:32.588443815 +0200
 +
+++ OpenCV-2.1.0/3rdparty/flann/flann.h 2010-06-08 01:15:06.912417891 +0200
 +
@@ -267,7 +267,7 @@ LIBSPEC int flann_compute_cluster_center
 +
 +
 +
#ifdef __cplusplus
 +
-};
 +
+}
 +
 +
 +
#include "flann.hpp"
 +
--- OpenCV-2.1.0/3rdparty/include/flann/constants.h.origin 2010-06-08 01:14:54.503416676 +0200
 +
+++ OpenCV-2.1.0/3rdparty/include/flann/constants.h 2010-06-08 01:15:06.912417891 +0200
 +
@@ -41,7 +41,7 @@ enum flann_algorithm_t {
 +
KMEANS = 2,
 +
COMPOSITE = 3,
 +
SAVED = 254,
 +
- AUTOTUNED = 255,
 +
+ AUTOTUNED = 255
 +
};
 +
 +
enum flann_centers_init_t {
 +
--- OpenCV-2.1.0/3rdparty/include/flann/flann.h.origin 2010-06-08 01:14:44.672417690 +0200
 +
+++ OpenCV-2.1.0/3rdparty/include/flann/flann.h 2010-06-08 01:15:06.912417891 +0200
 +
@@ -267,7 +267,7 @@ LIBSPEC int flann_compute_cluster_center
 +
 +
 +
#ifdef __cplusplus
 +
-};
 +
+}
 +
 +
 +
#include "flann.hpp"
 +
</source>
 +
== opencv_example ==
 +
=== Makefile ===
 +
<source lang="bash">
 +
CC=../../host/usr/bin/arm-unknown-linux-uclibcgnueabi-gcc
 +
all:
 +
        $(CC) -Wall -o opencv_example -L../../staging/usr/lib/ -I../../staging/usr/include/ -lopencv_highgui opencv_example.c
 +
clean:
 +
        rm -rf opencv_example
 +
</source>
 +
=== opencv_example.c ===
 +
<source lang=C>#include <stdio.h>
 +
#include <time.h>
 +
#include <opencv/cv.h>
 +
#include <opencv/highgui.h>
 +
 +
int main(int argc, char *argv[])
 +
{
 +
 +
    CvCapture* capture = cvCreateCameraCapture(CV_CAP_V4L2);
 +
    IplImage *img;
 +
 +
    if(!capture) {
 +
        printf("Can't get capture device\n");
 +
        exit(EXIT_FAILURE);
 +
    }
 +
 +
    /* Grab some picture because the first ones is very dark */
 +
    while (clock() / CLOCKS_PER_SEC < 3)
 +
        cvGrabFrame(capture);
 +
 +
    /* Get one picture and save it as test.jpg */
 +
    img = cvRetrieveFrame(capture, 0);
 +
    cvSaveImage("test.jpg", img, 0);
 +
 +
  cvReleaseImage(&img );
 +
  cvReleaseCapture(&capture);
 +
 +
  return EXIT_SUCCESS;
 +
}
 +
</source>
 +
[[Category: Software]]
 +
[[Category: Video]]

Latest revision as of 18:11, 4 September 2013

OpenCV 2.3

The buildroot openCV package is not available yet in the buildroot version used by ARMadeus, however I will explain a little workaround to cross-compile this graphical library and use it on your ARMadeus plateform. I was inspired by the Opencv 2.1 section downwards.

This section has been written using an APF51 with the git-trunk ARMadeus version.

Buildroot configuration

  • Install lib4vl

In your armadeus directory: 

$ make menuconfig

Package Selection for the target  --->
  Hardware handling  --->
    [*] libv4l
      [*]   v4l2-ctl
  • Take a look in...
Package Selection for the target  --->
  Libraries  --->
    Graphics  --->

... if the interesting format (jpg, png etc ...) for your application is checked.

Compiling and installing OpenCV-2.3.1

  • Prepare the directories
$ mkdir OpenCV-2.3.1
$ cd OpenCV-2.3.1
$ mkdir build
$ mkdir src
  • Get the source
$ cd src
$ wget http://sourceforge.net/projects/opencvlibrary/files/opencv-unix/2.3.1/OpenCV-2.3.1a.tar.bz2
$ tar xvjf OpenCV-2.3.1a.tar.bz2
$ cd ../
  • Patch the source

This (dirty?) patch fix a compatibility problem with the long double type on ARM plateforme (fabsl not available).

OpenCV-2.3.1.patch 

$ patch -p0 < OpenCV-2.3.1.patch
  • Build Makefile from CMake
$ cd build
$ cmake -DCMAKE_BUILD_TYPE=RELEASE -DCMAKE_TOOLCHAIN_FILE:PATH=your_armadeus_directory/buildroot/output/toolchainfile.cmake -DCMAKE_INSTALL_PREFIX=your_armadeus_directory/buildroot/output/staging/usr/ -DCMAKE_BUILD_TYPE=RELEASE ../src/OpenCV-2.3.1/

Check if no error and the install path. You can configure your OpenCV compilation with... 

$ cmake-gui
  • Build OpenCV-2.3.1
$ make && make install
  • Copy the libraries into your rootfs filesystem.

In your armadeus directory: 

$ cp buildroot/output/staging/usr/lib/libopencv_* buildroot/output/target/usr/lib/

Test & example

This test was made with a Logitech QuickCam Communicate STX.

Configure your Linux Kernel

In your armadeus directory: 

$ make linux-menuconfig

Check if the V4L driver is correctly checked: 

Device Drivers  --->
  <M> Multimedia support  --->
     <M>   Video For Linux

And configure your driver, in our case for the Logitech QuickCam Communicate STX: 

Device Drivers  --->
  <M> Multimedia support  --->
     [*]   Video capture adapters  --->
       [*]   V4L USB devices  --->
         <M>   GSPCA based webcams  --->
           <M>   ZC3XX USB Camera Driver

Reflash kernel and rootfs.

Build your application

In your armadeus directory 

$ cd buildroot/output/build
$ mkdir opencv_example
$ cd opencv_example

In this directory, copy these files:

Makefile

opencv_example 

$ make

Run the application test

On your APF board 

# modprobe videodev
# modprobe gspca_zc3xx

Where gspca_zc3xx corresponding to my logitech webcam.

Then run the opencv_example application et check the picture test.jpg.

OpenCV 2.1

Page under construction... Construction.png Informations on this page are not guaranteed !!

Forewords

This section explains how to (cross-)compile OpenCV 2.1.0 or later for your APF-board.

Pre-requisite

The CMake infrastructure has been integrated in Buildroot since the BR release 2011.02.

The CMake infrastructure is available in armadeus SDK since the armadeus-4.1 release (since it is based on BR release 2011.05).

Note Note: Using elder armadeus SDK requires having CMake 2.6 or later installed on the host system.


Build OpenCV

Note Note: The tutorial hereafter (patch and OpenCV configuration) is for the OpenCV 2.1.0 release.

This may changes in newer OpenCV releases. Updates are welcome ;-)


  1. Setup the CMake toolchain file:
    1. Using armadeus-4.1 SDK or later (or git view): this file is generated by buildroot and is located in armadeus-4.1/buildroot/output/toolchainfile.cmake.
    2. Using armadeus-4.0 SDK or former: the toolchainfile.cmake must be manually edited.
  2. Create source and build directories 
    mkdir -pv opencv-on-armadeus/{src,build}
  3. Grab the OpenCV source archive.
    cd opencv-on-armadeus/src && wget http://sourceforge.net/projects/opencvlibrary/files/opencv-unix/2.1/OpenCV-2.1.0.tar.bz2 && tar xvvjf OpenCV-2.1.0.tar.bz2
  4. Here, you'll have to apply this patch to avoid compilation failed: 
    patch -p0 < OpenCV-2.1.0.patch
  5. Run CMake (generate Makefiles) 
    1. cd ~/opencv-on-armadeus/build && cmake -DCMAKE_TOOLCHAIN_FILE:PATH=/path/to/toolchainfile.cmake ../src/OpenCV-2.1.0
    2. It will certainly complain about unfound libraries and some other things, so adjust these things running:
      cmake-gui
  6. Compile OpenCV libraries 
    VERBOSE=1 make


Note Note: cmake-gui
  • Click twice on Configure when you change something.
  • When configuring exit without any error, click on Generate to generate Makefiles.
  • If your configuration is too messy, reset it by deleting the cache (File/Delete Cache) or remove the CMakeCache.txt file in the build directory. Don't hesitate to do so if something (eg. paths) is wrong ;)
  • To see the cmake-command that corresponds to the configuration you have just set in cmake-gui: Tools/Show my changes


Available features (for armadeus-4.0 release or former)

CMake looks for all required tool in the path specified in toolchainfile.cmake; therefore, some options, targets, libraries, ... are not available:

  • Build:
    • Latex Doc  : Not available in Buildroot
    • New Python support  : Not available (require Python >=2.6, Buildroot provides Python 2.4)
    • Swing Python support : Not available (require Python >=2.6, Buildroot provides Python 2.4)
    • Octave support  : Not available in Buildroot
  • Python
    • Executable  : Not found (require Python >=2.6, Buildroot provides Python 2.4)
    • Include dirs.  : Found
    • Library  : Not found (require Python >=2.6, Buildroot provides Python 2.4)
  • With
    • V4L  : Disable it (Buildroot provides it, but linker failed)
  • OpenCV
    • 3rd party libs.  : You can enable it.


Note Note: You may need to enable some packages in your Armadeus configuration to get some libraries (libjpeg, libpng and libtiff) found by CMake.


Run OpenCV applications on your APF-board

  1. In the build directory, you should find a bin and a lib sub-directories. Copy them (at least the lib directory) on your target.
  2. export LD_LIBRARY_PATH=/path/to/the/OpenCVlibdir
  3. Run your application. You can try cvtest (some tests may fail because of missing resources), it will take a while... a long while ;)

See also

Appendices

OpenCV-2.3.1.patch

Index: src/OpenCV-2.3.1/modules/flann/include/opencv2/flann/dist.h
===================================================================
--- src/OpenCV-2.3.1/modules/flann/include/opencv2/flann/dist.h	2011-09-12 20:42:27.000000000 +0200
+++ src/OpenCV-2.3.1/modules/flann/include/opencv2/flann/dist.h	2012-02-05 15:10:28.715982724 +0100
@@ -60,7 +60,7 @@
 inline double abs<double>(double x) { return fabs(x); }
 
 template<>
-inline long double abs<long double>(long double x) { return fabsl(x); }
+inline long double abs<long double>(long double x) { return fabs(x); }
 
 
 template<typename T>

OpenCV-2.1.0.patch

--- OpenCV-2.1.0/3rdparty/flann/constants.h.origin	2010-06-08 01:14:22.171416516 +0200
+++ OpenCV-2.1.0/3rdparty/flann/constants.h	2010-06-08 01:15:06.912417891 +0200
@@ -41,7 +41,7 @@ enum flann_algorithm_t {
 	KMEANS = 2,
 	COMPOSITE = 3,
 	SAVED = 254,
-	AUTOTUNED = 255,
+	AUTOTUNED = 255
 };
 
 enum flann_centers_init_t {
--- OpenCV-2.1.0/3rdparty/flann/flann.h.origin	2010-06-08 01:14:32.588443815 +0200
+++ OpenCV-2.1.0/3rdparty/flann/flann.h	2010-06-08 01:15:06.912417891 +0200
@@ -267,7 +267,7 @@ LIBSPEC int flann_compute_cluster_center
 
 
 #ifdef __cplusplus
-};
+}
 
 
 #include "flann.hpp"
--- OpenCV-2.1.0/3rdparty/include/flann/constants.h.origin	2010-06-08 01:14:54.503416676 +0200
+++ OpenCV-2.1.0/3rdparty/include/flann/constants.h	2010-06-08 01:15:06.912417891 +0200
@@ -41,7 +41,7 @@ enum flann_algorithm_t {
 	KMEANS = 2,
 	COMPOSITE = 3,
 	SAVED = 254,
-	AUTOTUNED = 255,
+	AUTOTUNED = 255
 };
 
 enum flann_centers_init_t {
--- OpenCV-2.1.0/3rdparty/include/flann/flann.h.origin	2010-06-08 01:14:44.672417690 +0200
+++ OpenCV-2.1.0/3rdparty/include/flann/flann.h	2010-06-08 01:15:06.912417891 +0200
@@ -267,7 +267,7 @@ LIBSPEC int flann_compute_cluster_center
 
 
 #ifdef __cplusplus
-};
+}
 
 
 #include "flann.hpp"

opencv_example

Makefile

CC=../../host/usr/bin/arm-unknown-linux-uclibcgnueabi-gcc
all:
        $(CC) -Wall -o opencv_example -L../../staging/usr/lib/ -I../../staging/usr/include/ -lopencv_highgui opencv_example.c
clean:
        rm -rf opencv_example

opencv_example.c

#include <stdio.h>
#include <time.h>
#include <opencv/cv.h>
#include <opencv/highgui.h>

int main(int argc, char *argv[])
{

    CvCapture* capture = cvCreateCameraCapture(CV_CAP_V4L2);
    IplImage *img;

    if(!capture) {
        printf("Can't get capture device\n");
        exit(EXIT_FAILURE);
    }

    /* Grab some picture because the first ones is very dark */
    while (clock() / CLOCKS_PER_SEC < 3)
        cvGrabFrame(capture);

    /* Get one picture and save it as test.jpg */
    img = cvRetrieveFrame(capture, 0);
    cvSaveImage("test.jpg", img, 0);

  cvReleaseImage(&img );
  cvReleaseCapture(&capture);

  return EXIT_SUCCESS;
}
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