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2014-04-09 14:16:50 -0500 answered a question BlackBerry 10 and Momentics IDE

There are Step-by-Step instructions provided here.

2014-04-09 09:44:08 -0500 asked a question BlackBerry 10 and Momentics IDE

Hello, Are there any Step-by-Step Tutorials that make openCV functions availible from within a "Blackberry-Cascades-Project" created inside the Momentics IDE on a Windows 7 64-bit machine?

I already found HelloOpenCV, but i do not have "make" and "qcc" on Windows 7 64-bit. I tried to install make and then the Momentics IDE showed me an error "cannot find qcc". I know that it is something like a compiler...

Secondly, i also found Blackberry OpenCV, but there is no explanation on how to integrate everything within the Momentics IDE and a Cascades-project.

I am used to getting things done in Java and i do understand the concept of importing libraries from the Java perspective.

I found a Visual Studio Tutorial and wanted to ask if it is possible to use this to configure the Momentics IDE?

2013-07-16 11:31:49 -0500 asked a question Documentation authors

I am writing a scientific document and i have cited a website from the opencv documentation. The website used in the cite is:

Does someone know the author ?

2013-07-03 03:45:16 -0500 received badge  Nice Answer (source)
2013-06-13 16:32:29 -0500 commented question java openCV, Imgproc.accumulate(src,dst) unknown exception

found the error: i had a typo in path. question can be closed

2013-06-13 14:31:14 -0500 commented question java openCV, Imgproc.accumulate(src,dst) unknown exception

downvote?! give reason please. I will correct the issues.

2013-06-13 09:57:23 -0500 asked a question java openCV, Imgproc.accumulate(src,dst) unknown exception

I want to calculate the running average of 2 pictures (Later i am going to add more). I am using java opencv. i have written this piece of code, which throws an error in c++ code. I cannot understand why. Could someone clarify??

import org.opencv.core.Core;
import org.opencv.core.CvType;
import org.opencv.core.Mat;
import org.opencv.highgui.Highgui;
import org.opencv.imgproc.Imgproc;

public class BackgroundAverageTest {
    public static void main(String[] args) {
    Mat pic1 = Highgui.imread(pathToMyPic1);
    Mat pic2 = Highgui.imread(pathToMyPic2);
    Mat accumulated = new Mat(CvType.CV_32FC3);
    Imgproc.accumulate(pic1, accumulated);

Here is the Exception:

Exception in thread "main" java.lang.Exception: Unknown exception in JNI code {imgproc::accumulate_11()}
    at org.opencv.imgproc.Imgproc.accumulate_1(Native Method)
    at org.opencv.imgproc.Imgproc.accumulate(
    at tests.BackgroundAverageTest.main(
2013-06-11 02:42:13 -0500 commented question Using get() and put() to access pixel values in JAVA

As you mentioned already: It is probably due to the byte cast. Could you clarify why you use such a tricky approach to set and get values ?

2013-06-10 00:47:06 -0500 answered a question Motion Detection with OpenCV (C++)

You can check out this resource: .

Although its made for python, i guess it is possible to understand the general technique and adapt to some other language.

As long as your background is fixed, you can track any object with it.

2013-06-05 06:33:08 -0500 asked a question Destroy Java 'Mat'-Object

I am using OpenCV in Java. Is there a method that destroys a Mat object (deletes it from memory)?

2013-05-26 08:17:52 -0500 received badge  Teacher (source)
2013-05-26 06:30:28 -0500 commented answer please help me in configure the opencv for eclipse juno in java

the link lacks the step with "Native library location" and "add c++ dll", it also confused me when starting to program openCV in java.

2013-05-25 18:26:12 -0500 commented answer Face Detection through a webcam in java

check out this post for the answer: (dont forget to upvote the post)

2013-05-25 17:40:51 -0500 commented question please help me in configure the opencv for eclipse juno in java

If my solution is working for you: i would appreciate it you accepted it as a solution by clicking the accept sign.

2013-05-24 14:17:51 -0500 asked a question Method performance comparison

Which method is faster for retrieving a submat, adjustROI() or submat() ? I want to know it because im working with java and i got a loop over many images of size 1600*1200.

Thanks in advance.

2013-05-23 00:17:24 -0500 answered a question java.lang.IllegalArgumentException: Incomatible Mat from MatOfDMatch

Although Mr. Pavlenko was clear and has answered the question, I want to add something, namely using this code:

FeatureDetector fd = FeatureDetector.create(FeatureDetector.FAST);

If myImageKeyPointList is empty also an exception is raised (i guess that is the same reason as Mr. Pavlenko mentioned in his post):

Exception in thread "main" java.lang.IllegalArgumentException: Incomatible Mat
    at org.opencv.core.MatOfKeyPoint.<init>(
    at org.opencv.utils.Converters.Mat_to_vector_vector_KeyPoint(
    at org.opencv.features2d.FeatureDetector.detect(

Besides i am using openCV 2.4.5 and java.

2013-05-22 09:30:16 -0500 answered a question how do i create a runnable jar that use opencv

You must supply the c++ dll AND the openCV-jar to the jar file at jar creation time. Although i am not sure how to do it, i am sure about that this is the error, because the same error happens when forgetting to add the dll to the classpath.

2013-05-22 07:14:07 -0500 answered a question please help me in configure the opencv for eclipse juno in java

You have to do this (Step by Step explanation):
1.) Start eclipse, open new Project
2.) right click project, go into "properties"
3.) go into "Java Build path", click add external jars
4.) go into the folder where your jar is placed, "open"
5.) select the newly added jar and expand its "plus-sign"
6.) select "Native library location" and click edit
7.) here select the location where you have stored your c++ dll

If you do not know where your c++ dll and your jar file is:
-download openCV
-unpack it go into folder "build/java" (you will see opencv-245.jar)
-go into "build/java/x86" (you will see your dll)

2013-05-18 07:31:12 -0500 asked a question read smaller Mat 'pixel by pixel' while sliding over bigger Mat

I want to read a fixed-size-submat from a bigger Mat while sliding it over the bigger one pixel by pixel (or maybe 5 pixel by 5 pixel or somtheing like that, i hope you get the idea). Is there a predefined function for that in openCV, if so which one is it? (Besides i am using Java with opencv 2.4.5..) I have an idea how to write it myself in java using Mat.submat(a,b,c,d), but i thought that the underlying c++ dll implementation would be a lot faster.

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2013-05-02 07:10:07 -0500 commented question calculating and drawing histogram in java with opencv

Thanks for the side-note that it should be easy to adapt.

2013-05-02 05:32:45 -0500 asked a question calculating and drawing histogram in java with opencv

I have read the Tutorial on calculating and drawing histograms in c++. Unfortunately, i couldn't find the "histImage()"-method inside the Java API. Do I have to write a Histogram-function from scratch or has somebody experience with java openCV and could point me in the right direction respectively point to the corresponding methods in the java API.

2013-05-02 05:12:28 -0500 commented answer png compression

yep i found it out

2013-05-02 02:35:37 -0500 commented answer png compression

Actually i had to instantiate the "compression-vector" like this "MatOfInt mPngCompressionRate = new MatOfInt(Highgui.CV_IMWRITE_PNG_COMPRESSION,0);" gives 5000kb and "MatOfInt mPngCompressionRate = new MatOfInt(Highgui.CV_IMWRITE_PNG_COMPRESSION,9); gives 2000kb". (poor javadoc)

2013-05-02 02:32:20 -0500 received badge  Scholar (source)
2013-05-02 02:29:18 -0500 commented answer png compression

totally forgot about those pages, i hope they will help, i am going to post the result here, thank you

2013-05-02 01:45:36 -0500 edited question png compression

Why does the png-file-size increase? Here is the code (in Java):

Mat m = Highgui.imread("C:/img1.png");
Highgui.imwrite("C:/img1out.png", m);

Initially the "img1.png"-file is 900kb, but "img1out.png" becomes 2200kb! I have read that the compression in openCV is not as good as in other image-processing API's, but recently some compression has been added.

I tried out to do this here:

Mat m = Highgui.imread("C:/img1.png");
MatOfInt mPngCompressionRate = new MatOfInt(9);
Highgui.imwrite("C:/img1out.png", m, mPngCompressionRate);

But the size still goes up to 2200kb of "img1out.png". What am i doing wrong here ?