java - OpenCV pyrMeanShiftFilter in Processing--problems with matrix

Question

I'm trying to use the Mean Shift Function from OpenCV inside a program called Processing, which is a language based on Java. So far, I know that the function requires two mat and two double, [ pyrMeanShiftFiltering( Mat, Mat, Double, Double) ] and the mat needs to be 8 bits and 3 channels. But, when I run it, it only seems to work for the upper 3/4 th of the image and cuts out the rest.

Does anyone know how to get this function to run on the whole image?

sample image: cat.jpg

import gab.opencv.*;
import java.nio.*;
import org.opencv.imgproc.Imgproc;
import org.opencv.core.Mat;
import org.opencv.core.CvType;
import org.opencv.core.Core; 

OpenCV opencv;
Imgproc imgproc;

PImage canny;
PImage src, out;
Mat one, two;
double a = 20.0;
double b = 10.0;

void setup() {
  src = loadImage("cat.jpg");
  size( 429, 360);

  System.loadLibrary(Core.NATIVE_LIBRARY_NAME);  
  one = new Mat( width, height, CvType.CV_8UC3);
  two = new Mat( width, height, CvType.CV_8UC3);

  one = toMat(src);
  imgproc.pyrMeanShiftFiltering( one, two, a, b);
  out = toPImage(two); 
}

void draw() {
  image(out, 0, 0, width, height);
}

Mat toMat(PImage image) {  
  int w = image.width;  
  int h = image.height;  
  Mat mat = new Mat(h, w, CvType.CV_8UC3);  
  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;
}  

 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;
} 

Answer 1

The problem is that you are using rows where the columns should be and columns where the rows should be. Check the Mat documentation for more information.

so, whenever you have this:

new Mat( width, height, CvType.CV_8UC3);

invert the order

new Mat( height, width, CvType.CV_8UC3);

Also, I notice that you have a 4 channel images (ARGB) and the toMat function also have 4 channels, but you create a Mat with only 3 CV_8UC3, you should use 4 CV_8UC4 (not sure in java), and beware, normally opencv uses is BGRA !! so you may need to mix the channels correctly.

I hope this helps you