生成高品质缩略图算法的用法
请问下这个生成高品质缩略图算法的用法   谢谢～
import   java.awt.image.BufferedImage;

public   class   ImageScale   {

private   int   width;
private   int   height;
private   int   scaleWidth;
double   support   =   (double)   3.0;
double   PI   =   (double)   3.14159265358978;
double[]   contrib;
double[]   normContrib;
double[]   tmpContrib;
int   startContrib,   stopContrib;
int   nDots;
int   nHalfDots;

public   BufferedImage   imageZoomOut(BufferedImage   srcBufferImage,   int   w,   int   h)   {
width   =   srcBufferImage.getWidth();
height   =   srcBufferImage.getHeight();
scaleWidth   =   w;

if   (DetermineResultSize(w,   h)   ==   1)   {
return   srcBufferImage;
}
CalContrib();
BufferedImage   pbOut   =   HorizontalFiltering(srcBufferImage,   w);
BufferedImage   pbFinalOut   =   VerticalFiltering(pbOut,   h);
return   pbFinalOut;
}

/**
  *   决定图像尺寸
  */
private   int   DetermineResultSize(int   w,   int   h)   {
double   scaleH,   scaleV;
scaleH   =   (double)   w   /   (double)   width;
scaleV   =   (double)   h   /   (double)   height;
//   需要判断一下scaleH，scaleV，不做放大操作
if   (scaleH   > =   1.0   &&   scaleV   > =   1.0)   {
return   1;
}
return   0;

}   //   end   of   DetermineResultSize()

private   double   Lanczos(int   i,   int   inWidth,   int   outWidth,   double   Support)   {
double   x;

x   =   (double)   i   *   (double)   outWidth   /   (double)   inWidth;

return   Math.sin(x   *   PI)   /   (x   *   PI)   *   Math.sin(x   *   PI   /   Support)
/   (x   *   PI   /   Support);

}   //   end   of   Lanczos()

//
//   Assumption:   same   horizontal   and   vertical   scaling   factor
//
private   void   CalContrib()   {
nHalfDots   =   (int)   ((double)   width   *   support   /   (double)   scaleWidth);
nDots   =   nHalfDots   *   2   +   1;
try   {
contrib   =   new   double[nDots];
normContrib   =   new   double[nDots];
tmpContrib   =   new   double[nDots];
}   catch   (Exception   e)   {
System.out.println( "init   contrib,normContrib,tmpContrib "   +   e);
}

int   center   =   nHalfDots;
contrib[center]   =   1.0;

double   weight   =   0.0;
int   i   =   0;
for   (i   =   1;   i   <=   center;   i++)   {
contrib[center   +   i]   =   Lanczos(i,   width,   scaleWidth,   support);
weight   +=   contrib[center   +   i];
}