OpenCV error in Processing 4.0b2

Processing Libraries
#1

I’m preparing a workshop using Processing 4.02b, but OpenCV library seems to have an issue with permissions.

WARNING: Illegal reflective access by gab.opencv.OpenCV (file:/Users/Name/Documents/Processing/libraries/opencv_processing/library/opencv_processing.jar) to field java.lang.ClassLoader.sys_paths
WARNING: Please consider reporting this to the maintainers of gab.opencv.OpenCV
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release
NullPointerException

Any suggestion to run OpenCV again?

#2

This a java feature since java 11, but is normally (up to jdk11 at least) only a warning that you can ignore. Ideally you want the OpenCV library updated to module version that explicitly permits reflective access.

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#3

hence, what would be the solution, in particular to that NullPointerException?

#4

The problem is not the warnings themselves. The warnings are telling you the library is doing something it shouldn’t be. In this case, setting a private field to null in such a way that worked in JDK 8 and throws an exception in JDK 11 - the internal behaviour of ClassLoader has changed quite a bit.

Also see java - Processing 4 error: WARNING: Illegal reflective access by gab.opencv.OpenCV - Stack Overflow

#5

hi Neilcsmith
Thanks for the link. The solution for Processing 4 is here in this link

#6

Thanks for OpenCV for Processing 4.

However, I still got the error “A library used by this sketch relies on native code that is not available. UnsatisfiedLinkError: no opencv_java400 in java.library.path: :/Applications/Processing.app/Contents/Java/core/library/macos-x86_64:…”

Do you maybe know what can cause this?

#7

I am receiving the same exact error despite that fix. Have you been able to resolve this issue yourself?

#8

Yes, I solved it by copying the file “libopencv_java400.dylib” to /Applications/Processing.app/Contents/Java/core/library
Of course, with updated library from above. Let me know if it fixed your case.

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#9

I am new in Image/video processing field. I want to learn OpenCV in Processing 4.0b2.
I could not run the very first example “BackgroundSubtraction”. IDE throws the following messages:

Processing video library using bundled GStreamer 1.16.2
java.lang.NoSuchFieldException: sys_paths
at java.base/java.lang.Class.getDeclaredField(Class.java:2610)
at gab.opencv.OpenCV.addLibraryPath(Unknown Source)
at gab.opencv.OpenCV.initNative(Unknown Source)
at gab.opencv.OpenCV.(Unknown Source)
at BackgroundSubtraction.setup(BackgroundSubtraction.java:30)
at processing.core.PApplet.handleDraw(PApplet.java:2142)
at processing.awt.PSurfaceAWT$9.callDraw(PSurfaceAWT.java:1440)
at processing.core.PSurfaceNone$AnimationThread.run(PSurfaceNone.java:356)
OpenCV for Processing 0.5.4 by Greg Borenstein http://gregborenstein.com
Using Java OpenCV 2.4.5.0
IllegalArgumentException: Width (0) and height (0) cannot be <= 0
IllegalArgumentException: Width (0) and height (0) cannot be <= 0
IllegalArgumentException: Width (0) and height (0) cannot be <= 0
Could not run the sketch (Target VM failed to initialize).
For more information, read Help ? Troubleshooting.

At line no. 20 IDE shows the command " opencv.loadImage(video); " highlighted.

Please help me.

#10

Hello @bhaskar1955,

The example works with:

I did get this error:

image
image971×279 13.9 KB

And added this delay to correct that problem:

void setup() 
  {
  size(720, 480);
  video = new Movie(this, "street.mov");
  opencv = new OpenCV(this, 720, 480);
  
  opencv.startBackgroundSubtraction(5, 3, false);
  
  println(frameCount, video.width, video.height);
  
  video.loop();
  video.play();
  
  int t1 = millis();
  while (video.width == 0 )
    {
    //println(millis());
    if (millis() - t1 > 1000)
      {
      // Can add a message here if over 1000 ms or 1 s
      }
    }
  int t2 = millis();   
  println(t2-t1, video.width, video.height); 
  }

Relate discussion about that error:
https://forum.processing.org/two/discussion/23389/resizing-a-movie-possible-bug.html

Working:

image
image722×512 134 KB

Make an ASCII Video
#11

Thanks a lot glv for your kind and quick response. Soon I shall post my experience.

1 Like
#12

Yes, @glv , it worked. Thanks again. I hope you will help me in the future also.

Regards

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#13

Thanx a lot @Dazzid …!! This really help me. And also thanx @kkirklewski for the tip on moving the file.
I was going crazy trying to make it work on a mac M1 Monterey, processing 4.

Though this might help:
With the info on this current thread, and the following line of code (for gstreamer), I was able to run it correctly.

Instead of initializing the Capture instance like this:
video = new Capture(this, width, height);

Do it like this:
video = new Capture(this, 640, 480, “pipeline:avfvideosrc device-index=0 ! video/x-raw, width=640, height=480, framerate=30/1”);

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