import java.awt.FlowLayout;
import java.awt.image.BufferedImage;
import java.awt.image.WritableRaster;
import java.io.File;
import java.io.IOException;

import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;


public class Lab3 {


	public static void showImage(BufferedImage img, String title) {

		ImageIcon icon=new ImageIcon(img);
		JFrame frame=new JFrame();
		frame.setLayout(new FlowLayout());
		frame.setSize(200,300);
		JLabel lbl=new JLabel();
		lbl.setIcon(icon);
		frame.setTitle(title);
		frame.add(lbl);
		frame.setVisible(true);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	}

	public static BufferedImage toGray(BufferedImage buff){

		WritableRaster wr = buff.getRaster();
		int width = buff.getWidth();
		int height = buff.getHeight();

		int sum=0;

		for(int i=0; i<width; i++)
			for(int j=0; j<height; j++ ){

				if( wr.getNumBands() > 1 ){
					int R = wr.getSample(i, j, 0);
					int G = wr.getSample(i, j, 1);
					int B = wr.getSample(i, j, 2);

					int I = (int)(0.3*R + 0.59*G + 0.11*B);

					wr.setSample(i, j, 0, I);
					wr.setSample(i, j, 1, I);
					wr.setSample(i, j, 2, I);
				}

				sum += wr.getSample(i, j, 0);

			}

		System.out.println("mean : "+sum/(width*height));

		return buff;
	}

	public static double STD(BufferedImage buff){
		int numArray[] = new int[buff.getWidth()* buff.getHeight()];

		WritableRaster wr = buff.getRaster();
		wr.getSamples(0, 0, buff.getWidth(), buff.getHeight(), 0, numArray);

		double sum=0.0;
		double sd = 0.0;
		int length = numArray.length;

		for(double num: numArray)
			sum += num;

		double mean = sum/length;
		System.out.println("mean: "+mean);
		for(double num: numArray){
			sd += Math.pow(num - mean, 2);
		}

		return Math.sqrt(sd/(length-1));
	}
	public static void main(String[] args) throws Exception {
		// TODO Auto-generated method stub
		String file="C:\\download\\test_035.jpg";
		BufferedImage img=ImageIO.read(new File(file));

		showImage(img,"Color");

		//showImage(toGray(img),"Gray");
		double sd = STD(toGray(img));
		System.out.println("sd: "+sd);
	}

}