Interesting Image problem

[u sankarlal]

Hi all,
How to find the number of colors in a particular image, (image is in file format.) ?
Help me to proceed.
thanks

[Nathan Pruett]

I only had to modify one of my programs a little bit to get it to do this...

If you need any further explanations, please post...

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.filechooser.*;
import java.io.File;
import java.util.HashMap;
import java.awt.image.PixelGrabber;
 
public class ColorCounter extends JFrame
{
    private JButton  imagePanel;
    private JTextField numText;
 
    public ColorCounter()
    {
        super( "Color Counter" );
        imagePanel = new JButton();
        JScrollPane js = new JScrollPane( imagePanel );
        getContentPane().add( js, BorderLayout.CENTER );
        numText = new JTextField( 18 );
        numText.setEditable( false );
        JPanel p = new JPanel();
        p.add( numText );
        getContentPane().add( p, BorderLayout.SOUTH );
    }
 
    protected void frameInit()
    {
        super.frameInit();
 
        JMenuBar menuBar = new JMenuBar();
 
        JMenu file = new JMenu( "File" );
 
        JMenuItem open = new JMenuItem( "Open" );
        open.addActionListener( new OpenActivated() );
        file.add( open );
 
        menuBar.add( file );
 
        setJMenuBar( menuBar );
    }
 
    public static void main( String args[] )
    {
        ColorCounter cc = new ColorCounter();
        cc.addWindowListener( cc.new ExitActivated() );
        cc.setSize( 300, 300 );
        cc.setVisible( true );
    }
 
    private class ExitActivated extends WindowAdapter
    {
        public void windowClosing( WindowEvent event )
        {
            System.exit( 0 );
        }
    }
 
    private class OpenActivated implements ActionListener
    {
        public void actionPerformed( ActionEvent event )
        {
            JFileChooser fileChooser = new JFileChooser();
            ExtensionFilter filter = new ExtensionFilter();
            filter.addExtension( "gif" );
            filter.addExtension( "jpg" );
            filter.addExtension( "jpeg" );
            filter.setDescription( "Image Files" );
            fileChooser.addChoosableFileFilter( filter );
            fileChooser.setFileFilter( filter );
            int selected = fileChooser.showOpenDialog( imagePanel );
 
            switch( selected )
            {
                case JFileChooser.CANCEL_OPTION:
                    break;
                case JFileChooser.APPROVE_OPTION:
                    File f = new File( fileChooser.getCurrentDirectory(),
                            fileChooser.getName( fileChooser.getSelectedFile() ) );
                    String fileName = f.getAbsolutePath();
                    Image i = Toolkit.getDefaultToolkit().getImage( fileName );
                    MediaTracker mt = new MediaTracker( imagePanel );
                    mt.addImage( i, 0 );
                    try
                    {
                        mt.waitForAll();
                    }
                    catch( InterruptedException exception )
                    {
                    }
 
                    ImageIcon ii = new ImageIcon( i );
                    imagePanel.setIcon( ii );
                    ColorCounter.this.validate();
 
                    HashMap colorHolder = new HashMap();
                    int pixels[] = new int[ ii.getIconWidth() * ii.getIconHeight() ];
                    PixelGrabber pg = new PixelGrabber( i, 0, 0, ii.getIconWidth(),
                            ii.getIconHeight(), pixels, 0, ii.getIconWidth() );
                    try
                    {
                        pg.grabPixels();
                    }
                    catch( InterruptedException exception )
                    {
                    }
                    for( int j = 0; j < pixels.length; j++ )
                    {
                        colorHolder.put( Integer.toString( pixels[ j ] ),
                                new Integer( pixels[ j ] ) );
                    }
                    numText.setText( Integer.toString( colorHolder.size() ) );
                    break;
                default:
                    break;
            }
        }
    }
 
    private class ExtensionFilter extends FileFilter
    {
        private String description;
        private HashMap filters = null;
 
        public ExtensionFilter()
        {
            filters = new HashMap();
            setDescription( "undefined" );
        }
 
        public void addExtension( String extension )
        {
            filters.put( extension.toLowerCase(), this );
        }
 
        public String getDescription()
        {
            return( description );
        }
 
        public void setDescription( String description )
        {
            this.description = description;
        }
 
        public boolean accept( File f )
        {
            if( f != null )
            {
                if( f.isDirectory() )
                {
                    return( true );
                }
 
                String extension = getExtension( f );
                if( extension != null && filters.get( extension ) != null )
                {
                    return( true );
                }
            }
 
            return( false );
        }
  
        protected String getExtension( File f )
        {
            if( f != null )
            {
                String fileName = f.getName();
                int i = fileName.lastIndexOf( '.' );
                if( i > 0 && i < fileName.length() - 1 )
                {
                    return( fileName.substring( i + 1).toLowerCase() );
                }
            }
 
            return( null );
        }
    }
}

HTH,
-Nate