ImageIcon icon;
 try  {
   icon =  new  ImageIcon( new  URL(filename));
}
 catch  (Exception ex) {
   icon =  new  ImageIcon(filename);
}
 if  (icon.getIconWidth()>maxWidth) {
   icon =  new  ImageIcon(icon.getImage().getScaledInstance(maxWidth, - 1 , Image.SCALE_DEFAULT));
}

   public   byte [] makeThumbnail( byte [] fullImage)
  {
     
     ImageIcon iconFull, iconThumb;
      byte [] thumbImage =  null ;
     
      try  
     {
        iconFull =  new  ImageIcon(fullImage);
     }
      catch  (Exception ex) 
     {
         return  fullImage;
     }
     
     iconThumb =  new  ImageIcon(iconFull.getImage().getScaledInstance(THUMB_WIDTH, - 1 , Image.SCALE_DEFAULT));
     
     // а тут как-то надо выцепить byte[] из iconThumb...

      return  thumbImage;
  }

   public   byte [] makeThumbnail( byte [] fullImage)
  {

     ImageIcon iconFull, iconThumb;
      byte [] thumbImage =  null ;

      try 
     {
        iconFull =  new  ImageIcon(fullImage);
     }
      catch  (Exception ex) 
     {
         return  fullImage;
     }

     iconThumb =  new  ImageIcon(iconFull.getImage().getScaledInstance(THUMB_WIDTH, - 1 , Image.SCALE_DEFAULT));


     ByteArrayOutputStream out =  null ;

      try 
     {
        ImageIO.write((RenderedImage)(iconFull.getImage()), "jpg", out);
        thumbImage = out.toByteArray();
     }
      catch (Exception ex)
     {
        thumbImage =  null ;
     }

      return  thumbImage;

  }

  // #######################################################################################################
   public   byte [] makeThumbnail( byte [] imgBytes)// throws IOException
  { 
     ImageIcon i =  new  ImageIcon(imgBytes);
      int  width = i.getIconWidth();
      int  height = i.getIconHeight();

      int  sx = THUMB_WIDTH;
      int  sy = sx*height / width; // пропорционально вычислить


     ByteArrayInputStream baIStream =  new  ByteArrayInputStream(imgBytes);

     SeekableStream s = SeekableStream.wrapInputStream(baIStream, true);
     RenderedOp image = JAI.create("stream", s);
     ((OpImage)image.getRendering()).setTileCache( null );
      int  ww = image.getWidth();
      int  hh = image.getHeight();

      if (sx == - 1 )
     {
        sx = ( int )(ww * (( double )sy / hh));
     }

      if (sy == - 1 )
     {
        sy = ( int )(hh * (( double )sx / ww));
     }

     ByteArrayOutputStream baos =  new  ByteArrayOutputStream();
     image = scaleToPix(image, sx, sy);
     JAI.create("encode", image, baos, "PNG",  null );

      return  baos.toByteArray();
  }

  // ################################
   private  RenderedOp scaleToPix(RenderedOp image,  double  width,  double  height)
  {
      if (image ==  null )
         return   null ;

      int  ww = image.getWidth();
      int  hh = image.getHeight();

      float  fattX = ( float )(width / ww);
      float  fattY = ( float )(height / hh);

     Interpolation interp = Interpolation.getInstance(Interpolation.INTERP_BICUBIC_2);
     ParameterBlock parSC =  new  ParameterBlock();
     parSC.addSource(image);
     parSC.add(fattX); // x trans
     parSC.add(fattY); // x trans
     parSC.add( 0 .0f); // x trans
     parSC.add( 0 .0f); // x trans
     parSC.add(interp);

      try 
     {
         return  JAI.create("scale", parSC);
     }
      catch (Exception e)
     {
        e.printStackTrace();
         return   null ;
     }
  }