如要轉換的圖片：

轉換後在excel中的效果：

沒多大意義練練手:

import java.awt.Color;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.Locale;

import javax.swing.ImageIcon;

import jxl.Workbook;
import jxl.WorkbookSettings;
import jxl.format.Colour;
import jxl.read.biff.BiffException;
import jxl.write.Label;
import jxl.write.WritableCellFormat;
import jxl.write.WritableSheet;
import jxl.write.WritableWorkbook;

public class Helper {
	private  BufferedImage getBufferedImage(String filepath)
	{
		ImageIcon imgicon=new ImageIcon(filepath);
		 BufferedImage bufferedImage = new BufferedImage(imgicon.getIconWidth(),imgicon.getIconHeight(),BufferedImage.TYPE_INT_RGB);     

		 bufferedImage.createGraphics().drawImage(imgicon.getImage(), 0, 0,null);
		 return bufferedImage;
		 
	}
	
	private  Colour getNearestColour(Color awtColor) {  
	     Colour color = null;  
	     Colour[] colors = Colour.getAllColours();  
	     if ((colors != null) && (colors.length > 0)) {  
	      Colour crtColor = null;  
	      int[] rgb = null;  
	      int diff = 0;  
	      int minDiff = 999;  
	     
	      for (int i = 0; i < colors.length; i++) {  
	       crtColor = colors[i];  
	       rgb = new int[3];  
	       rgb[0] = crtColor.getDefaultRGB().getRed();  
	       rgb[1] = crtColor.getDefaultRGB().getGreen();  
	       rgb[2] = crtColor.getDefaultRGB().getBlue();  
	     
	       diff = Math.abs(rgb[0] - awtColor.getRed())  
	         + Math.abs(rgb[1] - awtColor.getGreen())  
	         + Math.abs(rgb[2] - awtColor.getBlue());  
	     
	       if (diff < minDiff) {  
	        minDiff = diff;  
	        color = crtColor;  
	       }  
	      }  
	     }  
	     if (color == null)  
	      color = Colour.BLACK;  
	     return color;  
	    }  
	public void exec(String convertFromImage,String createxls) throws Exception
	{
		
		WorkbookSettings ws = new WorkbookSettings();
	    ws.setLocale(new Locale("en", "EN"));
	    WritableWorkbook workbook = Workbook.createWorkbook(new File(createxls), ws);
	    WritableSheet s2 = workbook.createSheet("picture", 0);
	    BufferedImage buffimage=   getBufferedImage(convertFromImage);
	    int width=buffimage.getWidth();
	    int heigh=buffimage.getHeight();
	    for(int i=0;i<width;i++)
	    {
	        for(int h=0;h<heigh;h++)
		    {
	            WritableCellFormat greyBackground = new WritableCellFormat();
	            Color c = new Color(buffimage.getRGB(i, h));  
	           
	    	
			    greyBackground.setBackground( getNearestColour(c) );
			  
			    Label  lr = new Label(i, h, "", greyBackground);
		
			    s2.addCell(lr);
		    }
	    	
	    }
	    
	
	    

       //寫入Excel物件 
	    workbook.write(); 

	
	    workbook.close();
		
	}
	/**
	 * @param args
	 * @throws IOException 
	 * @throws BiffException 
	 */
	public static void main(String[] args) throws Exception {
		Helper helper=new Helper();

		System.out.println("輸入的圖片："+args[0]);
		System.out.println("輸出的excel："+args[1]);
		System.out.println("轉換開始");
		//轉換執行的方法引數 args[0]輸入的圖片路徑 args[1]輸出的excel路徑
//		helper.exec( "mslogo.jpg","1.xls");
		helper.exec(args[0],args[1]);
	}

}