Einlesen eines jpg-Bildes und Ermitteln der Breite.

Main.java

class Observer 
implements java.awt.image.ImageObserver
{ public boolean imageUpdate
  ( final java.awt.Image img, final int flags,
    final int x, final int y, final int width, final int height ) 
  { if(( flags & java.awt.image.ImageObserver.ERROR )!= 0 )
    throw new java.lang.RuntimeException( "ERROR" );
    if(( flags & java.awt.image.ImageObserver.ABORT )!= 0 )
    throw new java.lang.RuntimeException( "ABORT" );
    return(( flags & java.awt.image.ImageObserver.ALLBITS )== 0 ); }}

public class Main
{ public static void main ( final java.lang.String[] args )
  { java.awt.Image image = 
    java.awt.Toolkit.getDefaultToolkit().getImage( "example.jpg" );
    final java.awt.image.ImageObserver observer = new Observer();
    int width; while(( width = image.getWidth( observer ))< 0 );
    java.lang.System.out.println( width ); }}

// einfacher: ImageIO.read(...).getWidth();

Erzeugen eines jpg-Bildes

Main.java

public class Main
{ public static void main ( final java.lang.String[] args )
  { int  width = 800; int height =  600;
    int[] target = new int[ width * height ];
    for( int y = 0; y < height; y++ )
    { for( int x = 0; x < width; x++ )
      { final int r =(( int )( 128 + 128 * Math.tan
            ( 0.00001 * ( x - 30 )* y / width * height ))<< 16 )& 0xff0000;
        final int g =(( int )( 128 + 128 * Math.tan
            ( 0.00002 *( width - x )*( y - 30 )/ width * height ))<<  8 )& 0xff00;
        final int b =(( int )( 128 + 128 * Math.tan
            ( 0.00003 * x * y / width * height ))<<  0 )& 0xff; 
        target[ x + y * width ]= 0xff000000 | r | g | b; }}
    for( int j = 0; j <( int )( 1 ); ++j )
    { int x =( int )( Math.random() * width );
      int y =( int )( Math.random() * height );
      int r =( int )( Math.random() * 256 );
      int g =( int )( Math.random() * 256 );
      int b =( int )( Math.random() * 256 );
      for( long i = 0; i <( long )( 1E12 * Math.random() ); ++i )
      { if( x > 0 && x < width && y > 0 && y < height )
        { r = r < 0 ? 0 : r > 255 ? 255 : r;
          g = g < 0 ? 0 : g > 255 ? 255 : g;
          b = b < 0 ? 0 : b > 255 ? 255 : b;
          final int rgb =(( r << 16 )&0xff0000)|(( g << 8 )&0xff00)|( b & 0xff );
          target[ x + y * width ]= 0xff000000 | rgb; }
        x +=( int )(( Math.random() - 0.5 )* 3 ); 
        y +=( int )(( Math.random() - 0.5 )* 3 ); 
        r +=( int )(( Math.random() - 0.5 )* 3 ); 
        g +=( int )(( Math.random() - 0.5 )* 3 );
        b +=( int )(( Math.random() - 0.5 )* 3 ); }}
    java.awt.image.BufferedImage output = 
    new java.awt.image.BufferedImage
    ( width, height, java.awt.image.BufferedImage.TYPE_INT_RGB );
    output.setRGB(0, 0, width, height, target, 0, width );
    java.io.BufferedOutputStream out = null;
    try { out = new java.io.BufferedOutputStream
      ( new java.io.FileOutputStream( "generated.jpg" )); }
    catch( final java.io.FileNotFoundException fileNotFoundException )
    { throw new java.lang.RuntimeException( fileNotFoundException ); }
    com.sun.image.codec.jpeg.JPEGImageEncoder encoder = 
    com.sun.image.codec.jpeg.JPEGCodec.createJPEGEncoder( out );
    com.sun.image.codec.jpeg.JPEGEncodeParam param = 
    encoder.getDefaultJPEGEncodeParam( output );
    param.setQuality( 1.0f, false);
    encoder.setJPEGEncodeParam( param );
    try { encoder.encode( output ); out.close(); }
    catch( final java.io.IOException ioException )
    { throw new java.lang.RuntimeException( ioException ); }}}

Animation

http://javaboutique.internet.com/TumbleItem/