如何在java中通过Bilinear Interpolation缩小图像？

Question

我正在尝试读取图像，将其放大到80 * 60，然后通过双线性插值方法将结果图像缩小5次。但是我得到了这个错误：线程中的异常＆＃34; main＆＃34; java.lang.ArrayIndexOutOfBoundsException：4800。有人可以帮我吗？

这就是我所做的：

import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.awt.image.DataBufferByte;
import java.awt.image.WritableRaster;
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;

import javax.imageio.ImageIO;

public class BiInterpolationTest {

    public static int zh;
    public static int zw;


    public static void main(String[] args) throws IOException {
        // TODO Auto-generated method stub


        int[][] savedImage;

        File  f = new File ("F:\\Java\\Gray Scale Images\\3.jpg"); 
        savedImage = readimage(f);
        BufferedImage grayImage = new BufferedImage(savedImage.length, savedImage[0].length, BufferedImage.TYPE_BYTE_GRAY);

        for (int i =0 ; i<savedImage.length ; i ++){
        for (int j=0 ; j<savedImage[0].length ; j++){
                int rgb = savedImage[i][j];
                rgb = (rgb<<16)|(rgb<<8)|(rgb);
                grayImage.setRGB(i, j, rgb);

                BufferedImage zoomin =ScaledImage(grayImage, 80,60);
                 zh = zoomin.getHeight();
                 zw = zoomin.getWidth();


        byte[] tempArr;
            tempArr = extractBytes(zoomin);
                // TODO Auto-generated catch block

        byte [] zoomout;
        zoomout = bilineraInterpolation(tempArr , 5); 
        InputStream in = new ByteArrayInputStream(zoomout);
        BufferedImage bImageInterpolated;
        try {
            bImageInterpolated = ImageIO.read(in);
            ImageIO.write(bImageInterpolated, "jpg", new File(
                    "F:/new-darksouls.jpg"));
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        }

        }

    }

        public static BufferedImage ScaledImage(Image img, int w , int h){

        BufferedImage resizedImage = new BufferedImage(w , h , BufferedImage.TYPE_BYTE_GRAY);
        Graphics2D g2 = resizedImage.createGraphics();
        g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
        g2.drawImage(img, 0, 0, w, h, null);
        g2.dispose();
        return resizedImage;
        }
        /////////////////////////////////////
        public static byte[] extractBytes (BufferedImage Image) throws IOException {

             BufferedImage bufferedImage = new BufferedImage(Image.getHeight(), Image.getWidth(), BufferedImage.TYPE_BYTE_GRAY);

             // get DataBufferBytes from Raster
             WritableRaster raster = bufferedImage .getRaster();
             DataBufferByte data   = (DataBufferByte) raster.getDataBuffer();

             return ( data.getData() );
            }    


     public static int[][] readimage(File filename){
            BufferedImage img;

            try {
                img = ImageIO.read(filename);

                // Gray_scaled Image output

                int width = img.getWidth();
                int height = img.getHeight();
                ImagePro.fw=width;
                ImagePro.fh = height;
                int [][] readimageVal = new int [width][height];
                for (int i = 0; i<height ; i++){
                    for (int j =0  ; j<width ; j++){

                        Color c = new Color(img.getRGB(j, i));
                           int r= (int)(c.getRed() * 0.299)&0xff;
                           int g = (int)(c.getGreen() * 0.587)&0xff;
                           int b = (int)(c.getBlue() *0.114)&0xff;
                           int avg = ((r+b+g));

                        readimageVal[j][i] = avg;
                            }
                            }
                return readimageVal;

            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            return null;
        }


     public static byte[] bilineraInterpolation(byte[] ImgData, int ratio) {

       int wf = zw*ratio;
       int hf = zh*ratio;
       byte[] tempArr = new byte[wf*hf] ;
       int A, B, C, D, x, y, index, g ;
       float x_ratio = ((float)(zw))/wf ;
       float y_ratio = ((float)(zh))/hf ;
       float x_diff, y_diff ;
       int in = 0 ;
       for (int i=0;i<hf;i++) {
           for (int j=0;j<wf;j++) {
               x = (int)(x_ratio * j) ;
               y = (int)(y_ratio * i) ;
               x_diff = (x_ratio * j) - x ;
               y_diff = (y_ratio * i) - y ;
               index = y*zw+x ;

               // range is 0 to 255 thus bitwise AND with 0xff
               A = ImgData[index] & 0xff ;
               B = ImgData[index+1] & 0xff ;
               C = ImgData[index+zw] & 0xff ;
               D = ImgData[index+zw+1] & 0xff ;

                        g = (int)(
                       A*(1-x_diff)*(1-y_diff) +  B*(x_diff)*(1-y_diff) +
                       C*(y_diff)*(1-x_diff)   +  D*(x_diff*y_diff)
                       ) ;

               tempArr[in++] = (byte) g ;                                   
           }
       }
       return tempArr ;
   }
     }