Re: Image Thinning using JAVA

On 6/26/2012 8:15 PM, John B. Matthews wrote:


You got me interested on that one. I made a really simple test program
because of time constraints.

What I found was that if you just did a ColorConvertOP to a PNG or a
JPEG image, the image was in fact fairly dark. But if you then convert
that image to a compatible image it looks really good in gray scale.

Here's the simple code.

package com.knutejohnson.test;

import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.io.*;
import javax.imageio.*;
import javax.swing.*;

import com.knutejohnson.classes.ImageUtilities;

public class PNGtoGray extends JPanel implements ActionListener {
     private BufferedImage bi;

     public PNGtoGray(BufferedImage bi) {
         this.bi = bi;

         setPreferredSize(new Dimension(bi.getWidth(),bi.getHeight()));
     }

     public void actionPerformed(ActionEvent ae) {
         bi = ImageUtilities.convertToGray(bi);
         bi = ImageUtilities.convertToCompatible(bi);
         repaint();
     }

     public void paintComponent(Graphics g) {
         g.drawImage(bi,0,0,null);
     }

     public static void main(final String[] args) {
         EventQueue.invokeLater(new Runnable() {
             public void run() {
                 try {
                     BufferedImage bi = ImageIO.read(new File(args[0]));
                     JFrame f = new JFrame("PNGtoGray");
                     f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
                     PNGtoGray ptg = new PNGtoGray(bi);
                     f.add(ptg,BorderLayout.CENTER);
                     JButton b = new JButton("Conver to Gray");
                     b.addActionListener(ptg);
                     f.add(b,BorderLayout.SOUTH);
                     f.pack();
                     f.setVisible(true);
                 } catch (IOException ioe) {
                     System.out.println(ioe);
                 }
             }
         });
     }
}

package com.knutejohnson.classes;

import java.awt.*;
import java.awt.geom.*;
import java.awt.image.*;
import java.io.*;
import java.util.*;
import javax.imageio.*;
import javax.imageio.stream.*;
import javax.imageio.plugins.jpeg.*;

public class ImageUtilities {
     public static void writeJPEG(RenderedImage image, float quality,
File file)
      throws IOException {
         if (quality < 0.0f || quality > 1.0f)
             throw new IllegalArgumentException("0.0 < Quality < 1.0");
         ImageWriter writer = null;
         Iterator iter = ImageIO.getImageWritersByFormatName("JPEG");
         if (!iter.hasNext())
             throw new IOException("No Writers Available");
         writer = (ImageWriter)iter.next();
         if (file.exists())
             file.delete();
         ImageOutputStream ios = ImageIO.createImageOutputStream(file);
         writer.setOutput(ios);
         JPEGImageWriteParam iwp = new JPEGImageWriteParam(null);
         iwp.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
         iwp.setCompressionQuality(quality);
         writer.write(null,new IIOImage(image,null,null),iwp);
         ios.flush();
         writer.dispose();
         ios.close();
     }

     public static BufferedImage convertToGray(BufferedImage image) {
         BufferedImage gray = new BufferedImage(image.getWidth(),
          image.getHeight(),BufferedImage.TYPE_BYTE_GRAY);
         ColorConvertOp op = new ColorConvertOp(
          image.getColorModel().getColorSpace(),
          gray.getColorModel().getColorSpace(),null);
         op.filter(image,gray);
         return gray;
     }

     public static BufferedImage scaleImage(BufferedImage src, double sx,
      double sy, int interpolationType) {
         AffineTransformOp op = new AffineTransformOp(
          AffineTransform.getScaleInstance(sx,sy),interpolationType);
         return op.filter(src,null);
     }

     public static BufferedImage scaleImage(BufferedImage src, double sx,
      double sy, RenderingHints hints) {
         AffineTransformOp op = new AffineTransformOp(
          AffineTransform.getScaleInstance(sx,sy),hints);
         return op.filter(src,null);
     }

     public static BufferedImage convertToCompatible(BufferedImage image) {
         GraphicsEnvironment ge =
          GraphicsEnvironment.getLocalGraphicsEnvironment();
         GraphicsDevice gd = ge.getDefaultScreenDevice();
         GraphicsConfiguration gc = gd.getDefaultConfiguration();

         BufferedImage compatible =
gc.createCompatibleImage(image.getWidth(),
          image.getHeight());

         if (compatible.getType() == image.getType())
             return image;

         ColorConvertOp op = new ColorConvertOp(
          image.getColorModel().getColorSpace(),
          compatible.getColorModel().getColorSpace(),null);

         return op.filter(image,compatible);
     }
}

--

Knute Johnson