Using Mat in openCV using java

Question

What is the correct way to use Mat class in openCV (using java)

Mat Class ==> org.opencv.core.Mat and do I have to use BufferedImage when I want to read image into Mat. please show me Code answer

import java.awt.image.BufferedImage;
import java.awt.image.DataBufferByte;
import java.io.File;
import java.io.IOException;

import javax.imageio.ImageIO;

import org.opencv.core.*;

public class opencv {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        BufferedImage img1 = null, img2 = null;
        try {
            img1 = ImageIO.read(new File("c:\\test.jpg"));
          //  img1 = ImageIO.read(new File("c:\\Fig2.tif"));
           System.out.print(img1.getHeight());
        } catch (IOException e) {
        }

        //byte[] pxl1 = ((DataBufferByte) img1.getRaster()).getData();
        //Mat src1 = new Mat("");
        //Core.addWeighted(Mat1, alpha, Mat2, beta, gamma, dst);

    }

}

Chris K · Accepted Answer · 2016-02-24 22:19:38Z

1

Assuming your image is 3 channel:

public Mat fromBufferedImage(BufferedImage img) {
    byte[] pixels = ((DataBufferByte) img.getRaster().getDataBuffer()).getData();
    Mat mat = new Mat(img.getHeight(), img.getWidth(), CvType.CV_8UC3);
    mat.put(0, 0, pixels);
    return mat;
}

and the reverse:

public BufferedImage toBufferedImage(Mat mat) {
    int type = BufferedImage.TYPE_BYTE_GRAY;
    if (mat.channels() > 1) {
        type = BufferedImage.TYPE_3BYTE_BGR;
    }
    byte[] bytes = new byte[mat.channels() * mat.cols() * mat.rows()];
    mat.get(0, 0, bytes);
    BufferedImage img = new BufferedImage(mat.cols(), mat.rows(), type);
    final byte[] pixels = ((DataBufferByte) img.getRaster().getDataBuffer()).getData();
    System.arraycopy(bytes, 0, pixels, 0, bytes.length);
    return img;
}

edited Feb 24, 2016 at 22:19

answered Feb 24, 2016 at 22:13

Chris K

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2 Comments

Muath Over a year ago

alright thx for explaining, do I have to use BufferedImage? this gives exception on .tif images how can i solve this

Chris K Over a year ago

Probably the reason you see an exception is because the BufferedImage you are providing is null. ImageIO doesn't support TIFF without adding some libraries. See here: stackoverflow.com/questions/2898311/…

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