java语言的科学与艺术（灰度图像）

import acm.graphics.*;
import acm.program.*;

public class imageConvert extends GraphicsProgram {
    public void run(){
        GImage image = new GImage("Penguins.jpg");
        image = applyAveragingFilter(image);
        add(image);
    }
    /*
     * Creates a new image by applying an averaging filter to the original.
     * Each pixel in the original image is replaced by a grayscale pixel with the 
     * average luminosity of the current pixel and its four immediate neighbors.
     */
    private GImage applyAveragingFilter(GImage image) {
        int[][] array = image.getPixelArray();
        int height = array.length;
        int width = array[0].length;
        for(int i = 0; i < height; i++) {
            for(int j = 0; j < width; j++) {
                int xx = averageNeighborLuminosity(array, i, j);
                array[i][j] = (0xFF << 24) | (xx << 16) | (xx << 8) | xx;
            }
        }
        return new GImage(array);
    } 
    
    /*
     * Computes the average luminosity of the pixel at array[i][j] and its four
     * immediate neighbors (up, down, left, and right).
     */
    private int averageNeighborLuminosity(int[][] array, int i, int j) {
        int sum = getLuminosity(array, i, j);
        int count = 1;
        if(i > 0) {
            sum += getLuminosity(array, i - 1, j);
            count++;
        }
        if(i < array.length - 1) {
            sum += getLuminosity(array, i + 1, j);
            count++;
        }
        if(j > 0) {
            sum += getLuminosity(array, i, j - 1);
            count++;
        }
        if(j < array.length - 1) {
            sum += getLuminosity(array, i, j + 1);
            count++;
        }
        return GMath.round((double) sum / count);
    }
    
    /* Determines the luminosity of the pixel at array[i][j] */
    private int getLuminosity(int[][] array, int i, int j){
        int pixel = array[i][j];
        int red = (pixel >> 16) & 0xFF;
        int green = (pixel >> 8) & 0xFF;
        int blue = pixel & 0xFF;
        return GMath.round(0.299 * red + 0.587 * green + 0.114 * blue);
    }
}