OpenCV cv::Mat <==> Processing PImage Converter Functions

MatImage.pde

import java.nio.*;
import org.opencv.core.Mat;
import org.opencv.core.CvType;

// Convert PImage (ARGB) to Mat (CvType = CV_8UC4)
Mat toMat(PImage image) {
  int w = image.width;
  int h = image.height;
  
  Mat mat = new Mat(h, w, CvType.CV_8UC4);
  byte[] data8 = new byte[w*h*4];
  int[] data32 = new int[w*h];
  arrayCopy(image.pixels, data32);
  
  ByteBuffer bBuf = ByteBuffer.allocate(w*h*4);
  IntBuffer iBuf = bBuf.asIntBuffer();
  iBuf.put(data32);
  bBuf.get(data8);
  mat.put(0, 0, data8);
  
  return mat;
}

// Convert Mat (CvType=CV_8UC4) to PImage (ARGB)
PImage toPImage(Mat mat) {
  int w = mat.width();
  int h = mat.height();
  
  PImage image = createImage(w, h, ARGB);
  byte[] data8 = new byte[w*h*4];
  int[] data32 = new int[w*h];
  mat.get(0, 0, data8);
  ByteBuffer.wrap(data8).asIntBuffer().get(data32);
  arrayCopy(data32, image.pixels);
  
  return image;
}

For error

A library relies on native code that's not available.
Or only works properly when the sketch is run as a 32-bit  application

Make sure your main program (such as in void setup()) loads the native OpenCV library:

import org.opencv.core.Core;
...
System.loadLibrary(Core.NATIVE_LIBRARY_NAME);

Any idea why my image looks like this?

Mat m2 = new Mat();
Imgproc.cvtColor(m, m2, Imgproc.COLOR_RGB2RGBA);

Fixed the issue for me. My cam is 3 chan, not 4 chan.

Source: https://github.com/atduskgreg/opencv-processing/blob/master/src/gab/opencv/OpenCV.java#L1210