assuming, you're talking about desktop-java here (android is a total different story),
convert your Mat to a BufferedImage, then draw it the usual way:
Mat m = Highgui.imread("some.png");
int type = BufferedImage.TYPE_BYTE_GRAY;
if ( m.channels() > 1 ) {
Mat m2 = new Mat();
Imgproc.cvtColor(m,m2,Imgproc.COLOR_BGR2RGB);
type = BufferedImage.TYPE_3BYTE_BGR;
m = m2;
}
byte [] b = new byte[m.channels()*m.cols()*m.rows()];
m.get(0,0,b); // get all the pixels
BufferedImage image = new BufferedImage(m.cols(),m.rows(), type);
image.getRaster().setDataElements(0, 0, m.cols(),m.rows(), b);
// later:
public synchronized void update(Graphics g)
{
g.drawImage(image,0,0,this);
}
Using System.arraycopy will give you 2 times speedup.
public Image toBufferedImageArrayCopy(Mat m){
int type = BufferedImage.TYPE_BYTE_GRAY;
if ( m.channels() > 1 ) {
type = BufferedImage.TYPE_3BYTE_BGR;
}
int bufferSize = m.channels()*m.cols()*m.rows();
byte [] b = new byte[bufferSize];
m.get(0,0,b); // get all the pixels
BufferedImage image = new BufferedImage(m.cols(),m.rows(), type);
final byte[] targetPixels = ((DataBufferByte) image.getRaster().getDataBuffer()).getData();
System.arraycopy(b, 0, targetPixels, 0, b.length);
return image;
}
Hi berak, you mentioned that android is a total different story, could you care to share examples on performing the same operation on android? I am currently trying to do a simple thresholding on an image on android but like you said, this approach doesn't work.
@jiarongkoh , for android, look at matToBitmap / bitMapToMat , and then draw it with an ImageView or such.
As for showing image in Java, I'd share some info here. This following example takes an image from the system and show it on a frame using ImageIO class. User enters the name of the image using the command prompt and then the program shows the same image on the frame. The image is read from the system by using ImageIO.read(File file) method.
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.*;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
public class ShowImage extends Panel {
BufferedImage image;
public ShowImage() {
try {
System.out.println("Enter image name\n");
BufferedReader bf=new BufferedReader(new
InputStreamReader(System.in));
String imageName=bf.readLine();
File input = new File(imageName);
image = ImageIO.read(input);
} catch (IOException ie) {
System.out.println("Error:"+ie.getMessage());
}
}
public void paint(Graphics g) {
g.drawImage( image, 0, 0, null);
}
static public void main(String args[]) throws
Exception {
JFrame frame = new JFrame("Display image");
Panel panel = new ShowImage();
frame.getContentPane().add(panel);
frame.setSize(500, 500);
frame.setVisible(true);
}
}
Tags: image, image in Java
OpenCV java wrapper doesn't include Iamshow class But I found someone who posted this Iamshow class, I didn't try it yet you may try it yourself and update me too...
Also try this link I found it useful.
Asked: 2013-08-06 10:01:39 -0600
Seen: 6,666 times
Last updated: Sep 25 '14
