public   class  JAIUtils
    {

         public    void  createThumbnail(String imageName, String thumbnailName,  int  maxSize,  boolean  preserveRatio)
            {

                PlanarImage image = JAI.create("fileload", imageName);
                 if  (image ==  null )
                    {
                         return ;
                    }

                 float  wScale = ( float ) maxSize / ( float ) image.getWidth();
                 float  hScale = ( float ) maxSize / ( float ) image.getHeight();
                // If we want to preserve the aspect ratio, pick the smaller
                // scale.
                 if  (preserveRatio)
                    {
                         float  scale = Math.min(wScale, hScale);
                        // Don't make the image larger than it already is.
                         if  (scale >  1 . 0 )
                            {
                                scale =  1 .0F;
                            }
                        wScale = scale;
                        hScale = scale;
                    }

                ParameterBlock pb =  new  ParameterBlock();

                pb.addSource(image); // The source image
                pb.add(wScale); // The xScale
                pb.add(hScale); // The yScale
                pb.add( 0 .0F); // The x translation
                pb.add( 0 .0F); // The y translation
                pb.add( new  InterpolationBilinear()); // The interpolation

                // Create the scaled image.
                PlanarImage thumb = JAI.create("scale", pb,  null );
                // Write out the image as a PNG.
                JAI.create("filestore", thumb, thumbnailName, "JPEG",  null );
                
               
            }

    }