sample sketch for "OpenCV for Processing" library...

opencv_test.pde

//
// sample sketch for "OpenCV for Processing" library...
//
String image_url = "nike.jpg";
Mat test_img;

void setup() {
  size(640, 480);
  initOpenCV();
}

void draw() {
  Mat img = loadImageMat(image_url);
  image(img, 0, 0);

  if (frameCount % 30 == 0) {
    println("fps=" + frameRate);
  }
}

opencv_utils.pde

import gab.opencv.*;
import org.opencv.core.*;
import org.opencv.imgproc.*;

OpenCV opencv;
void initOpenCV() {
  opencv = new OpenCV(this, width, height);
}

Mat loadImageMat(String url) {
  PImage pimage = loadImage(url);
  
  Mat argb_mat = new Mat(pimage.height, pimage.width, CvType.CV_8UC4);
  OpenCV.toCv(pimage, argb_mat);

  ArrayList<Mat> channels = new ArrayList<Mat>();
  Core.split(argb_mat, channels);

  ArrayList<Mat> reordered = new ArrayList<Mat>();  
  reordered.add(channels.get(3)); //B
  reordered.add(channels.get(2)); //G
  reordered.add(channels.get(1)); //R
  
  Mat bgr_mat = new Mat(argb_mat.rows(), argb_mat.cols(), CvType.CV_8UC3);
  Core.merge(reordered, bgr_mat);    
  return bgr_mat; 
}

PImage convertToPImage(Mat src) {
  PImage pimage = createImage(src.cols(), src.rows(), ARGB);
  
  if (src.channels() == 1) {
    Mat bgra_mat = new Mat(src.rows(), src.cols(), CvType.CV_8UC4);
    Imgproc.cvtColor(src, bgra_mat, Imgproc.COLOR_GRAY2BGRA);
    opencv.toPImage(bgra_mat, pimage);
  }
  else if (src.channels() == 3) {
    Mat bgra_mat = new Mat(src.rows(), src.cols(), CvType.CV_8UC4);
    Imgproc.cvtColor(src, bgra_mat, Imgproc.COLOR_BGR2BGRA);
    opencv.toPImage(bgra_mat, pimage);
  }
  else {
    opencv.toPImage(src, pimage);
  }
  return pimage;
}

void image(Mat img, float x, float y, float w, float h)
{
  PImage pimage = convertToPImage(img);
  image(pimage, x, y, w, h);
}

void image(Mat img, float x, float y)
{
  image(img, x, y, img.cols(), img.rows());
}